I used to be someone who started new saves. A lot. When I got to 15 saves, I stopped and started new sims out in one of the existing saves. I have recently decided to start out with a save in which I deleted most of the premades, edited game lots and added lots of my own. I am now in the process of moving households I like (as townies) or still want to play from other saves into this new save and deleting saves, basically consolidating saves. The good thing is they are all skilled and have careers. I am now down to 11 saves, but am still working on this. Just like OP, I feel this is a lot of work and a bit exhausting at times. I am not quite sure why I am doing it - perhaps to end up with a save with a very small number of weirdly dressed, pear-shaped single townies with adopted children?
Wow, I really mentioned save/saves a lot in this post!
