Break down the game into its key components
1. Field walking
2. Break out
3. Front man tactics
4. Mid player tactics
5. Back man tactics
4. The snap shot
5. Moving
6. Moving and shooting
7. Communication
8. Timing
9. Personal skills (left handed, right handed, profile, fitness, potting up etc)
10. Ending the game
11. etc
and set up drills that will help to improve these areas. For example moving and shooting can be done by hanging a small object like a bottle a distance away (this can be changed) and have your guys start behind a bunker. Walk out both left and right sided, and slowly at first walk to another bunker shooting the target. 9/10 your players will shoot too low. Adjust and keep doing it. When you are comfortably hitting the target, try to get faster. And faster. Soon, if done often enough, you will be able to move and shoot accurately and with speed. Watch the Pros. Look at how they hold the gun, is it tilted a certain way? Do they loop a thumb over the barrel to support it while moving? Do they use a piece of equipment that would change your set up to be able to hold a gun like Greenspan?
Basically you have to break it all down, and then draw up drills to train for them. Scrims will only get you so far in life (fun as they are) but drills are what maketh the player. Doing drill after drill on breakouts and breakout skills for a whole day will see an increase in players alive after 10 seconds. A whole day of back guys laning, and front guys trying to make spots up the field (for 20 secs at a time) will force your players to increase their chances. At the very least you will know who will not make the cut
And for goodness sake, don't allow them to shoot all their paint over the chrono
Someone has to control these days though. You need structure. Planned days for different drills. Everyone get there early, sort out guns before you get to training (no use fixing guns in the beginning few hours). All players give feedback. Captains/managers especially give individual feedback.....its their team. Write everything down. Make people fight for their spot in the A squad.