also the reservior is like your fuel tank its not a perfect vessel ,
if your filled to the cap 2" may be a lot of fluid but if you are filled to the fill line 2" isnt very much because the container is tapered to fit the fender
average is an ounce per second and you say you were running 4-5 pulls 8-12 sec, thats anywhere from 40-70 seconds under boost so using about 50oz isnt unexpected
if you ever test the system youll see there is a considerable amount of pressure at 20psi and that the pressure seems to top out at 22 pounds of boost , so 20psi is using alot of alky, it has to because you are running more timing and could be on a stock ic , the better the IC the less you may need , the duttneck improves flow but its still just a stock core. hot summer air also needs more alky to keep the inlet temps down .
ive run a jug from the flat area near top to the low sender in 5 passes on a dual nozzle... thats close to 100oz at 23psi
im leaned back a little but still use about 1.5oz per second (m10 and an M15 nozzle)
time to be worried is when the bottle goes down without using it (leaking), or that it doesnt seem to go down (bad pump)
i highly recomend getting the alky tester from razor and check your system regularly for psi and you can also safely look for any leaks
how high do you fill your reservior ?
after looking at my last fast log when my correction went up through first gear and a recent log on another 600+ hp car using razors alky logging kit in which the pressure dropped out from 150+ to 63psi and only came back to 150psi well after the initial hit off the line I would recommend that faster cars keep it filled near the top at all times