Yeah man. Trait doesn't matter so I try to go with young guys that I'm hoping will develop. Sometimes I'll do guys like my backup CB or RB that won't get much game time or game XP, and other times I'll do guys that are young that I need to depend on ASAP so I'll use it as a boost for guys that are already getting game XP and drill XP so they make an impact quicker.
My strategy with drill training is to train OL and WR on Offense and DL and DB on defense.
Offensively, I never re-sign OL for cap purposes so I'm always developing those guys and I am always developing a couple young WR cuz you can only keep 1-2 good ones long term.
Defensively, I try to develop LBs through game XP and focus training and then the DL and and DB with the drills. I'm always cycling DL and my 3rd and 4th corners because of cap purposes and it's easy to develop them when they're getting 700-1,000 XP/week from team drills. It's also easy to develop young backup safeties and DL that you can trade for mid/late round picks that help you when building a team and trying to stay under the cap.