Best place(s) to train 50 - 100 for low-tier characters?

You cannot do it in 8-10 minutes. It takes 3minutes and 20 seconds for each ingredient (it takes that long for the spawn to reach 100). You will go a minimum of 18 minutes per PQ.

From what I heard and experienced as well, it just took 3 mins for full spawn. Just kill mobs about 30 sec before it reached the max population (depend on how fast you can kill them) then you can finish it in time.
The fastest one I got so far took 16min34sec

50-60 and 90-100 are hell for me
-snip-
and 90-100.... all i can think of is pyramid pq, since i heard aliens got a big nerf, so i dont know if they are still good

it's kind of continual Tangyoon pq, give about 60-70% current exp for 10min if you can handle your line and help the others