Should I have not Shoved?

Just fold AK initially. Then you won't get drawn out on.

The call with ATs of 16xBB UTG was really bad, and might indicate the shove was a good approach at that table.

The reason for maybe not shoving would be that there is a narrow range you could profitable shove 16xBB UTG, and you wouldn't do it with AA/KK, so your hand is a little face up of AQ+/99-QQ and waited toward AK/AQ, so you may not get action.

If it doesn't look suspicious for you to limp, you could also limp it. That would be playing for a shove. It might be easier to play and often fold postflop than if you raised, if you don't get raised preflop and miss.

I typically don't shove with more than 15 blinds preflop. Unless I am in the SB and everyone else folded.

However it worked for you because you are a 70% favorite to double up and we are far from the money. And because you had been shoving a lot preflop with a shortish stack people might think you are shoving with a lot of Ax hands. The irony of course is that had you raised to 2x preflop and ATs called you could have jammed the flop with two overcards and a flush draw and he would have folded. And if you totally missed the flop you can check/fold and lose only 2 blinds.

Part of the reason I don't do it is because I will win only 2 1/2 blinds when everyone folds which is going to be less than 17% gain. Also we will rarely be 3-bet when we open UTG. Unless somebody has a monster.

70% favorite to double up, what more do you want? You have to double up 6-10x to get into the first three places in this size of tournament. Also, it was a good read that somebody will likely call you with a worse hand. I think the whole decision with AK in this situation is if somebody will likely call with worse. If yes, all-in is best.

Yeah, it was a good result getting called 70% to win.

I will shove 15xBB with medium strength hands from mid to late position. I am not sure it is a good play UTG with any hand. Obviously, AK is a hand you can do that with. It is a profitable shove compared with folding and you don't mind if everyone folds, as you would if you had AA. There are only a few hands that are reasonable shoves UTG for 16xBB.

It's fine to shove AQ or AK UTG for 16xBB.

I wouldn't do it all the time, but there are certain circumstances where I don't want calls, because the ICM makes those chips valuable, or because the table is like this, where too many people flat-call speculative hands even against a short stack - that would incline me to shove AKo / AQo, which have strong raw equity but poor postflop playability.

I would be more inclined to open the minimum at a table with players who will 3-bet bluff correctly, whereupon I can 4-bet shove and make more money (or just call if they shove i.e. A5s).

Stack size does matter, and I'd be more reluctant to do it with AQ than AK for obvious reasons. I would do it more often from later position than UTG. (particularly, say, at a final table where everyone is trying to avoid big flips - I would want to fold out hands like small-medium pairs from covering stacks that could reshove on me but that I could fold out by shoving first.)

My anecdote is, the first final table I made up here when I started playing again, first hand 8-handed guy shoves 23BB UTG with AQo. And next to act had KK.

I didn't mean shoving was the best play, but it is not a big mistake. It is usually not the best play, but obviously depends on the table.

Shoving AQo for 23xBB UTG is better than folding it. That it ran into KK is not that relevant, except there is a decent chance you will run into QQ+/AK, which is why it is only slightly profitable.

I think UTG 8-handed at a final table it can't possibly be the most profitable play and may even be unprofitable from a $EV standpoint when you consider how deep you are and what a disaster busting before the smaller stacks would be.

(And in these tournaments, probably more so, since a lot of people tend to play final tables way more fast and loose than they should, without much regard for pay jumps.)