Because you could have 110/118 or 112/116 and still have the same LSA.
That's why I cringe at how some guys select LSA. Or why. That's why I say set the events first and then the LSA will be close and you can manipulate things a bit to get what you want.
Intake valve closing is the big one for how many RPM you want to run per a given duration, and intake valve opening limits, or encourages reversion. It's all a balance.