If you aren't racing full speed (record is 4 minutes on a jumping trails)...10 to 15 minutes from mid point depending on the trail. 30 minutes from the top. This is full on dh, not bits and pieces. Lets put it like this, in florida the highest peak is 500 ft (if I remember right)...whistler mountain has 2200vert ft. 500vert ft are my xc race trails.
Hard to explain if you have never really dhilled. 15minutes doesn't sound like much but it woudl hurt most people. To start most fit peole can't last 5 to 7 runs (hands and legs give out)
I would hate having to stand around in line to take the lift back up.
Trust me, the 5 to 10 minute wait is NOTHING for thejoy of coming back down
...imagine your favorite technical trail you like to play on but is tough, and being able to ride it 20 times in one day. Imagine how much you would HAVE to improve.
With lift, a FAST run lasts 30minutes total. For in shape dhillers they can pull off 20 runs a day...my best is 15 and my hands were falling off and I was passing out from pain and anaerobic exhaustion.