as i mentioned in another recent answer, doses vary from person to person, just like at any level of the sport and normally, no one starts starts at massive doses. over time, the same amount of gear becomes less effective. you may have experienced this in your own cycling. there are many factors. a big one being genetics. usually, when we speak of genetics, we are talking about someones ability to grow massive. there is anohter aspect to genetics in todays game. genetics also determine how well someone can handle massive doses without dealing with side effects like cholesterol problems and organ touble. a lot of people would have problems very quick if they were to try what some of the pros are doing

another factor is what level they are at. there are a few top guys who are only competing in 1 big show a year. this is a very small percent of all the pros out there. doing only one or two shows allows them to take plenty of off time. for less known guys, trying to claw their way up in the ranks, it can be much harder to find the time to cycle off properly and let their body rest and recover. at times, the short term answer can be to up the dose but that can only be taken so far, for so long. eventually, if they dont take down time, their body will stop responding. you can see it if you follow the sport. take a guy who seems to be doing very well for a string of shows over a couple years and then all of a sudden, it falls apart. they stop coming in with the same size and conditioning. eventually, the fall out of the lime light...sometimes to return in a year or two. sometimes, they just burn themselves out or get taken out by complications, which we all know are due to heavy abuse of their body. my point is, the more gear being used, the more important off time is. "off" time means something different to each guy. i know some guys who come off all together. others stay on lower doses of test year round. 

from the people i know personally who compete in the IFBB, 2 grams of test is pretty average for an on cycle period, along with other anabolics, as well as high doses of gh and insulin. i don't personally know anyone who uses 5 grams of test alone, but total combined hormone levels of 5 grams is not shocking in the on season. also, i will note that outside of the actual last few months of contest prep, most guys i know, including myself, dont plan their cycles 100%. they add gear as they get it and switch to different compounds when the effect slows.