Just in time, @apm ! :) In the past few days, I scrolled through my profile, deleting every post (outside of two collections) I ever created. I could have waited some more weeks, but I wanted that content to be gone on my terms, not theirs - also, I wanted to check if there's anything that still needed to be rescued.
Doing this was an actually taxing process - one can imagine that there were both good and bad times during the 7.5 years I spent on Google+ - but I'm now happy that I had a final look at all of it instead of just waiting for someone at Google's HQ to flip a switch.
In hindsight, it is clear that most of my activity was mostly unsuccessful in all the "standard metrics" of a social platform: When I joined, I was just a little to late to still be considered for most early adopter's circles. When I started posting anyway, I tried getting my small hometown aboard by posting about it while using hashtags and location shares. When communities became a thing, I created one for my region. When collections were added, I created several to talk about niche interests of mine. When I had nothing else to do on the platform, I participated in photography themes and projects, even writing an app to challenge myself and others to new photo subjects. Most of this led to nothing, or only a small number of interactions.
For the last three years, the majority of my activity happened in two private communities that I mustn't really talk about due to some NDA - but it's safe to say that that turned out to be a big waste of time as well...
Not all of it was for nothing, though. I got to know a handful of interesting people, my photography is a lot better now than it was eight years ago - and I recognized that "being social" with random people without having a good topic to talk about just isn't my thing. :D