I used to be pretty cavalier about this. Then about a year ago, I turned off Web & App Activity as well as Location History in Google's data and privacy settings. I also deleted all my historical data. Google allows you to use their services without tracking everything you do. But the vast majority of people either don't know, or don't take the time to turn it off. And of course, some want it on...
While all Google services still work for me, they are not nearly as useful. For example, Google Maps no longer suggests places I regularly navigate to, like my home. And my Google Now newsfeed is full of celebrity gossip and other generic junk I would never read.
I also suspect it's working because ads I see when browsing are completely unrelated to me, like women's cosmetic products. Also, email confirmations from airlines no longer result in an automatic calendar appointment. And of course, when I go to Google Takeout to download or delete my data, there is nothing there. In the past I could see my activity in all it's gory detail.
The one setting I left 'on' is YouTube History. I use YouTube a lot. It's 90% of my TV viewing. So I like having "Recommended" videos that are in-sync with my interests and other YouTube channel subscriptions. That's how I discover interesting new content beyond my current subscriptions. YouTube knows my interests extremely well.
I know Google still has a lot of my personal data, like my CC numbers in Google Pay, Contacts, Calendar, and a copy of every digital photo I've ever taken. To name a few. But with all the tracking turned off, I feel a little less like "The Product."
At the same time, I also turned off data tracking in the Alexa app. Deactivated my Facebook account. Deleted unneeded apps on my phone. And reviewed all permissions on the apps I kept. Hopefully I'm a troublesome target.