How about 50 targets spread over 30 lanes.
10 lanes of 1 target.
3 lanes of 2 standers
2 lanes of 2 kneelers
15 lanes of 2 sitting targets.
1min 30secs for a 2 target lane, 1min for standing lanes and 1min for single target lanes.
I make that 38.5minutes of 'shooting time'.
Current 25 lanes @ 2 mins = 50mins 'shooting time'
OK so extra 5 lanes gives extra string pulling, arse scratching and nose picking time, but gives you 180 shooters in 2 sessions, 10 per session 'feed-on' and you've got 200 shooters in 2 sessions.
Single target and standing lanes spread equally over the course to avoid bunching.