Nearly all opponents who raise before the flop will follow it up with a continuation bet on the flop. Not all opponents however will fire the second bullet with an unimproved hand. When you get a rare chance to see a showdown when someone bets the turn with an unimproved hand, you should make a note of this and most important, write down what the bet size was in proportion to the pot size.
Noting that your opponent will fire multiple bullets with a non-paired hand is important, but it will be rare that you’ll be able to see them showdown a hand often enough to know the rate they do this. Of course if they are fire multiple bullets in nearly every pot they’re involved in, then you can be quite sure they make this play often. The more important thing that you can take away as a read within a short session against an opponent like this is how he bets his made hands versus his bluffs.
Some opponents will have a very definitive pattern here. So if you get to see an AK opponent go to showdown with an unimproved hand, and then get to see them go to showdown with a made hand, you want to note the differences in how they bet these two hands. A lot of opponents (especially at micro and small stakes) are not very balanced in how they bet their bluffs versus their made hands. Note everything you see about the differences, and try and relate their betting pattern to a ratio of the pot size.
For example, if you see someone bet an unimproved hand on the flop for a 1⁄2 sized pot bet on the flop, but they bet a made hand for slightly larger or 3/4ths the pot size bet on the flop, this will likely be a pretty reliable betting tell. If you get to see it more than once, you can almost ink it, and assume it is. Most of the better players won’t vary their bet sizing much or at all, as you’re told in most books and by other players not to, but you will spot some that do. You’ll know in this example when your opponent is betting weak, they’re weak, and when they bet strong, they’re strong. You might see the opposite of this, or any other combination of betting patterns, and different ones also on the turn. So don’t only note that this opponent is an AK, but how they bet their hands as well (you should do this with all opponents of course, but especially true when you see opponents who are firing multiple bullets).
The best thing to do is you are up against an AK player is to raise the flop if you miss, since raising the turn can get expensive. Also if you have some kind of modest holding like a small pocket pair that doesn’t have much improvement equity (ability to become an even stronger hand) when behind, you’re sometimes best to raise as well. This way you don’t find yourself in a spot calling multiple bullets with a really marginal hand that will rarely improve. Also this will allow you to take initiative back in the hand if they do just call, and then you can check the turn or later turn your hand into a bluff with more credibility. Just because someone is an AK doesn’t mean they won’t have a hand sometimes. You don’t want to invest too much with mid pair or an under pair to the board, unless you feel very confident in your read. If you hit the flop hard and have position it’s best to call their flop bet and raise the turn or call when they bet again.