Clean install wipes apps and index, not data on other partitions. Users panic thinking files are gone when Explorer just opens empty default folders.
First thing I install after network drivers: filename search. Before browser, sometimes. Need to locate old profile backups on D: immediately.
Where files actually survive
Secondary partitions, Windows.old if upgrade not clean wipe, external drives untouched. Search D: and E: first, rebuild index per volume.
Rebuild timing
Full index of a terabyte archive runs in background. Usable partial results appear quickly. Leave it indexing while you reinstall apps.
See also: Search across multiple drives without the lag, Portable tools for fixing other people's PCs.