Dont know which charts you use, but there are nash charts for pushfold that are accurate. Google for Jennifear Charts. At the Bubble you Push a bit wider against ppl who you cover and call a bit less against ppl who cover you, but not like too drastic. Its hard to calculate bubble spots. I know that ICMIZER can do this for up to some tables, but its way more important for your calling ranges than for your push ranges. Some ppl argue that you can push wider as nash, since the people are calling less than they should, but im not supporting this , because first you will learn wrong gameplay which will make moving up harder for you later. Second even on lower stakes ppl are not calling so much less than they should. Third If you call less, youll also get less value if called. Also the push ranges even with known calling ranges are not that much wider that most ppl awesome.

tldr;: Learning Nash Push/Fold Ranges is the first step to become a successfull MTT Player. There is no need to differ from it(imho).

I think getting Nash ranges down is essential but there are a ton of spots where adjusting them is a good idea. On bubble we should shove wider than Nash vs those we have covered if they don't seem prone to gamble (sometimes ATC vs midstacks when there are a bunch of shorties left in the field), and should be calling way tighter than Nash vs those who cover us (assuming many players shorter than us).

Early ITM I think we can shove a bit wider than Nash with shortish stack in big field tourneys (like when 400+ paid), because laddering up is worth way less than chance to go deep, even if we make slightly -chipEV shoves (may be wrong here but it is my approach). Final table bubble plays a lot like bubble but knowing villains is even more important. Some players play very tight with mid stack trying to make FT with low risk, others are 'going for the win' and very happy to flip for their stack, so will be calling pretty wide. Adjust accordingly.

I think ICM dictates we should be pretty hesitant to call off our stack with less than 60% equity vs range on final 2 tables, but I'm just starting to learn the math so can't say I'm sure. We should still be shoving pretty close to Nash, but tighten if we know that someone left to act is calling especially wide. Every chip we can lose is worth a lot more than chips we can win, and we'd really prefer not to gamble without a good edge.

Especially if we are midstack and there are many shorter stacks, we should be very risk averse on final table. Laddering up is meh, but busting in 8th when 3 people had way less chips than you is lighting your ROI on fire.

Also consider that a lot of great players will minraise weakest and strongest hands in Nash ranges, even at stacks as low as 10bb. It's a more difficult strategy than open shoving, but likely higher EV if you pick right spots and you've got good ranges for R/C and R/F.