Nope, percent cannot be at 100. You have to have balance as an option. Percent and Amount are there for if you wanted to deposit a portion to a different account. Lets say you want 100 to go into a spending account, and 75% go into checking.
This is what it would look like:
1 Amount $100
2 Percent 75%
999 Balance
Would tell it first to take 100 to put into your spending account regardless of how much you make. Then it takes 75% of what's left and deposits it into your checking account. Finally it has to have the Balance as the last option option to tell it what to do with any remaining compensation. That's all balance does. Anything left after other splits is caught under balance. It has to be last(999) because if it were to deposit your entire balance there would be nothing left to split off.