Especially since you are new to the shirt, keep working full ROM. You need to learn the groove and you can't do that with boards. Do whatever you want for assistance work but the main shirt work NEEDS to be to your chest. I would suggest reverse bands and chain work.
With the full ROM work you can better work on your competition technique as well. Use the boards too much and you will adapt a technique that is better for boards. Not competition. This is why a lot of bench only guys bomb out in my opinion. You see videos of guys hitting 60 billion pounds off a three board then can't get anything to touch in a meet. Those guys have shitty technique.
I think more advanced guys can benefit from doing board work just because their technique is going to be better than someone who just started using a shirt. Even with the boards, they can maintain full ROM form.
Finally, lockout is all triceps (and form). Work the shit out of those every bench workout.