I think this is a good suggestion. I switched over to the SLED with the Varget rounds not only to verify that it worked but also since I always do single fire with new loads. It definitely helped to make me take more time.
I also neglected to do any off hand practice. Not that running a few en blocs offhand 10 days before the match will make a big difference. Will try it tomorrow.
Don't wast good bullets on off hand practice. HXP makes good off hand fodder.
I can only tell you what works for me.
When I go to the range it's very "dedicated"
If I'm looking to see how a load works I bring either the lead sled or from and rear bags and shoot supported to see how the rifle and load work together.
If I'm working on "shooting" I will shoot as needed.
Ex: If I bring out the M1 or AR I will shoot as if I was in a match. This is also where I get my zero's.
All my rifles are based of a 100 yard no wind zero shooting prone with sling although will shoot with my front arm on a sand bag.
I will only repeat what I should have listened to many years ago. Do not get to hung up on load "development" let some one with know skills shoot your rifle with HXP. Get a good base line.
Same with your reloads. Don't waste to much time with loads. I think 40 grains is a bit light BUT I do have good results with light loads with both cast and FMJHP match.
Keep at it. As for rushing shots....very easy to do.
Last match I had a failure to feed and panicked a bit. I still found myself finishing early.
Breath....deep breath between each shot. Don't hold your breath just pause.
Natural point of aim is a key thing to work on also.