FWIW, I did the uplift at BPW for the first time on Friday. I lost count but I think I only got 7 or 8 runs in, and that's with being first in the queue when it opened and on the last bus up. It only took about 7 minutes of actual driving per run, but another 5-8 min of waiting/loading/unloading, and 2-15 minutes of riding/walking back to the uplift from wherever the trail ended (they don't all end near the uplift). Going to my van for quick lunch break took about 10-20 min of riding as well, because the uplift starts a long way from the car park. And the uplift only runs from 10 till 4, whereas the park is open 9-5.I got 5 full runs to the top at BPW and you can beat the uplift.
Even with a fixed battery, you could do at least 10 runs: 5 leisurely runs in the morning (9-11 am), 2 hour break to recharge (11-1), and 5 more in the afternoon (1-3). Might even get a partial charge (3-4) and a couple more runs (4-5) after that, so call it 11-13 runs total. You also have the flexibility to do any trail (with any ending point) without a time penalty, session shorter sections, visit the skills area, quickly go back to the van for repairs/breaks, etc.
With a removable battery and Avinox or CYC motor, 20+ runs is doable. The climb takes about 15 min and descent 5 min, so about 3 runs per hour, and you can ride for about 7 hours with an hour for lunch. That's nearly 3x the runs you get with an uplift and nearly 2x the number with a fixed battery.