it's a deceptive figure the ITM, you would think that having a higher ITM would immediately mean that you make more money or have a higher ROI %. However it's usually not the case. If you have a high ITM figure it means (generally) that you will also finish second more often than first, having a high ITM will help you a lot don't get me wrong, but increasing your distribution to have more 1st place finishes has way more benefits.
Benefits include, having a lower ITM%, which sounds funny, but that basically means you take less time to finish games, you bust out on average earlier. Less game time on average means you are able to play many more over the course of a week or month, resulting in more $/hour. This depends on if you play in sets or play continuously and if you play high volume or multitable of course. The more games you play the more important saving time is.
The other thing a lower ITM will do is basically boost your 1st place finish distribution. Most of the time when i see players with high ITM it is generally because they play too tight of a range and don't take enough risks before the bubble hits, this means they have less chips on the bubble, tend to play smart and sneak into the money, however they are almost always left with a chip disadvantage once you get to HU, meaning more 2nd place than first place finishes.
Anyways, to answer your question, 37-40% is generally where the really good players land, if you are at 44% i would suggest that you don't really have that high of a sample, (no, 1000 games is not much of a sample size) and the variance hasn't distributed yet, or you are playing low level games where getting a huge ITM and less of a 1st place distribution is basically how you win, as many players go crazy early on and you are almost always left with a chip disadvantage.