A factory reset is often chosen to solve a storage problem, which makes the choice you make immediately afterward the one that determines whether the problem actually gets solved or just gets postponed. Restore everything back exactly as it was through Migration Assistant, and you'll likely be back to the same available-space number within a week, because whatever accumulated over years comes back over years' worth of files, not none of them. This is the decision that matters most in the first hour after a reset, and the cleanup habits worth building in the weeks after it.
Migration Assistant versus a fresh start: what you're actually choosing
Migration Assistant, run from a Time Machine backup or directly from your old Mac, restores your entire user account — apps, settings, files, and all the accumulated cruft — in one pass. It's the right choice when you reset for a hardware issue, a corrupted system installation, or you're moving to new hardware and simply want continuity. It is not, by itself, a cleanup, because it restores everything including whatever caused the original storage problem.
A fresh setup, where you sign into iCloud and manually reinstall only what you need, is slower up front but is the actual solution if storage bloat was part of why you reset in the first place. You choose what comes back, in what order, which means the folders that silently grew to 40GB over three years don't automatically reappear.
A middle path many people don't realise exists: Migration Assistant lets you choose specific items to bring across rather than an all-or-nothing restore. If you back up first, you can selectively migrate Documents and Desktop while leaving Applications and Library data to reinstall fresh — keeping your files without dragging every accumulated app cache along with them.
What iCloud brings back automatically, and when
If you sign into iCloud on the freshly reset Mac, several things repopulate without any action from you, and it's worth knowing the order and pace so you're not confused by what seems to be happening on its own:
- Photos, if iCloud Photos is enabled, begins syncing immediately — full-resolution downloads can take hours or days depending on library size and connection speed
- Contacts, Calendars, Reminders, Notes sync quickly, usually within minutes
- Desktop and Documents, if you had this enabled before, restore automatically once you re-enable it, which is worth doing deliberately rather than by habit if disk space was part of the problem
- Messages in iCloud restores conversation history over time, though attachments may lag behind text
None of this restores your locally installed applications, developer tools, or caches — those need explicit reinstallation, which is exactly the opportunity a fresh setup gives you to be selective.
What to deliberately skip or delay
The value of a reset is the chance to not bring back the things that got you here. Worth genuinely reconsidering rather than reflexively restoring:
- Old iOS device backups you'd stored via Finder — if you haven't needed to restore a specific device from one in over a year, there's little reason to recreate that folder structure again
- Every developer tool you've ever tried — reinstall Xcode, your primary language runtimes, and daily tools; skip the one-off things you tested once and never used again
- Desktop and Documents sync, if it was quietly filling your iCloud storage and local disk simultaneously with files you'd forgotten about — worth auditing in iCloud's web interface before re-enabling
- Old application support data for apps you're not certain you'll reinstall — if you're not restoring the app itself, its settings folder has nothing to attach to anyway
Rebuilding developer tooling without restoring the old bloat
If you're a developer, this is the single best opportunity to fix accumulated dependency footprint rather than recreate it. Reinstall your package managers fresh, and if you were previously on npm or Yarn Classic across many projects, consider switching to pnpm at this point — its shared content-addressable store (~/Library/pnpm/store) means you won't rebuild the same multiplied node_modules problem project by project as you re-clone your repositories.
Clone projects back from git rather than restoring their node_modules and build artefacts from backup — you lose nothing (both regenerate from source), and you start the new install with none of the accumulated staleness the old ones had.
Checking your progress honestly
After the first week of normal use post-reset, check About This Mac → Storage Settings again and compare against what you had immediately after the reset finished. Some growth is expected and fine — you're reinstalling real tools you use. What's worth investigating is growth that outpaces what you've deliberately installed, which usually means something is regenerating the same pattern that caused the original problem (an over-eager sync setting, a build tool with unbounded caching, a habit of never clearing Downloads).
Setting up Time Machine again, deliberately
After a reset, it's worth reconsidering your backup setup rather than automatically pointing Time Machine at the same destination drive with the same settings as before. If the drive was nearly full of old backups spanning years, this is a natural point to start a fresh backup history rather than layering new backups onto an already-strained drive — Time Machine manages its own retention automatically, but starting clean on a reset Mac avoids any ambiguity about which backups correspond to the machine's current state versus its pre-reset one.
A short checklist for the first week after reset
- Choose Migration Assistant (selective) or fresh setup, deliberately, based on why you reset
- Re-enable iCloud services one at a time rather than all at once, so you can see what each one costs in disk space
- Reinstall developer tools from scratch rather than restoring accumulated caches
- Skip restoring old iOS backups and application support folders for apps you're not reinstalling
- Check Storage Settings after a week and investigate any growth that doesn't match what you've deliberately added
Where VolumeLens comes in
A week or two after a reset, once the essentials are back and installed, it's worth a fresh look at the disk to confirm the reset actually solved what it was meant to solve rather than just deferring it. VolumeLens gives you that view — a map of exactly what's using space, sized honestly — so you can catch an old pattern reappearing early, before it becomes the reason for another reset a few years from now.