[nanobuilds]

Three fresh Google accounts on different US residential proxies. Two browsed with specific personas (fisherman, fitness). The third did nothing for five days.

Google was more aggressive than I expected. 17 new ad interests from a single session. By Day 1 it was already removing interests and replacing them. Not adding to your profile. Rewriting it. The control didn't move once in five days.

I built a Mac app (MirrorMask) that does this against your real profiles. Happy to answer questions about the methodology.