To be perfectly honest, I wish Crash 4 didn't have the N. Verted mode or the Perfect Relics. If there wasn't so many requirements to completing the game 106%, then I'd say it's the absolute best Crash game in every way. The regular gems, flashback tapes and time trial relics would've been the 106% requirements for me, and I also would've made the alternate timeline levels their own stages, and I MEAN their own stages. I wouldn't call playing half or two thirds of the same level after you're done playing as that character a whole different level, or at least where that Cortex/Dingodile/Tawna segment ends, then the level ends as well. This game has so much padding and repetition it isn't even funny.
I also would've just removed that last section where you play as Crash/Coco in The Crate Escape, or at least have it so the physics weren't so wonky. And, when it comes to the time trials, I think the Triple Spin is okay, and an alright reward for finishing the game, but I would've preferred the Crash Dash power up from other games. Again, I don't find the Triple Spin bad by any means, but I think the Crash Dash would've been better. Also would've been great if the game didn't have so many obnoxiously hidden crates.
I really wish Toys For Bob looked at all of that and at least thought that it was a bit much and go back to tone it down a bit, because Crash 4 is a good game, but the 106% requirements are literally bursting at the seams.