I previously used my partner's Google account to watch on YouTube and it had built up recommendations based on what I previously watched since I didn't use the subscriptions, but one day it all just disappeared and only showed recommendations from my partner's subscriptions. I'd prefer if they implemented a user driven exploration system rather than attempting to guess what I want but it must be useful to be able to change how it works without modifying the user interface. I eventually gave up and used my own account with now 32 subscriptions and it's better than it was although it shows a lot of videos I've already watched. It throws in a few videos from other channels but it's mostly from the subscriptions.