Going in mid-Sept Solo. Should I reserve a day/time or not really a time saver? Obviously don't know the weather yet.
You may be too late to reserve. The choice is reserve or plan to wait in a long line. On a rainy day the line will be short so that is not necessarily a bad choice as long as the Tower is not clouded in; here we were with a reservation on a rainy day a few years ago.
https://janettravels.wordpress.com/2016/05/16/the-eiffel-tower-in-the-rain/
If you WALK up (great excercise!), you don't need reservations. Double-check, but I believe it's still true post-Covid. Just find the short line at the other tower leg.