this post is about flat bench press. I want to know is it better to stop a couple inches before your chess or barly touch your chess. second to fully extend or lock your elbows or to just before they lock.
In general it is best to get as full a range of motion as possible, without locking. So, I would definately touch the chest at the bottom of a bench press (or use dumbells that allow you to go even lower and get a good stretch across your chest). At the top you can stop just short of lockout or even push through the normal lockout position and round your upper back to push the bar up a few more inches.