@reallylongnickname I didn't ever do much work directly on them. I progressed to Planche Pushup work as soon as I could. I'd suggest you do the same by working on something like Leaned Forward Pushups if you want to improve your Planche ANDD your L-Sit at the same time.
I'm pretty sure I can hold over a minute now since I can hold a Tuck Planche for nearly that long.