The whole point with the extra landing lag is not so much that you have to keep track of it when you know it'll be there, but rather when you forget to keep track of it.
Ledgejumping, failing, getting juggled only to finally land 10 seconds later experiencing the one thing you didn't expect to happens, 17 frames of lag. Juggle starts all over again, or you just eat a fsmash. The main thing is that whatever you do, if your opponent noticed you upBing on the stage and keeps track of it, there is no way he can miss a punish when you finally land. He just has to run at you and shieldgrab whatever aerial you use to cancel the lag.
tl;dr: Watch your footing, or die.