Those who survive 3 hours of play automatically go into "all in mode" every next hand at 3:01.

"Most players will be extra tight for sure", me too. No matter how long it takes and no matter how tight the players are at the beginning, I expect an interesting game and a good fight!
Not in this weekend's format.
If we reach a running time as long as 3 hours the average stack is still kinda big, no need to go allin. Let's say we are in HU already after 3 hours, that's 300k in chips in circulation and the big blind is 1500/3000. So even is someone has a 3:1 chip advantage the small stack would still have 33 big blinds.
With this slow blind increase and a 250bb starting stack I doubt we will see preflop allins with AJ or other nonsense. The only incentive that rewards aggressive play is the big bounties. Collecting 2 bounties has the same worth as becoming first, even though first of course gets at least 200$ (100$ for 1st place, his own and 2nd place's bounty worth 50$ each).