It's always one of my big late spring projects, deadleading the lilacs. I've got a couple small ones in back shading the little pond, which are easy. Then there's the massive old one in front
(pictured in this thread:
https://www.helpfulgardener.com/forum/viewtopic.php?p=126190&highlight=spring+flowers#126190 middle of the page )
which is about sixty feet in circumference and has literally thousands (well literally well over a thousand) of blooms.
Deadheading it is a project. I can't do it all in one work session, so I just keep plugging away at it. But I don't mind, keeps me out in the sun and bird song and all those spent blossoms are buckets and buckets full of greens for the compost pile.
I assume anyone reading here in the Lilacs forum is aware that you need to deadhead (cut the blossoms off before they set seed) to keep it beautiful next year. Lilacs have big heavy seeds that don't fly or travel. So to keep this years seedlings from competing too much with last year's, since they will likely be all in proximity, it tends to bloom well only every other year, if allowed to set seed. The off years will have only a few blooms. To me the deadheading work is worth it to have a tree that looks like the picture, every year. The deadheading and some pruning is all I ever do to it.