(Army) Everyone has "minimums" and in peacetime, that's about all we get. Ours are 140 hrs a year with NVG, Night, Hood, Sim, and NBC requirements included as part of that total.
During the more exciting times, you fly what you have to. My slowest year was probably 100 hrs and busiest year probably 300 (military time).
Mission times vary. Our fuel endurance is typically 2.5 hours but "hot" refuel allows us to continue the mission without too much interruption. Typical peacetime missions back at the ranch are 1.5-2.5 hrs. Our current mission requires a lot of patrolling so our flights can be 4 to 6 hours or more but it does still vary. Our "Crew Rest/Fighter Management" policy allows us to fly up to 8 hours of day flight or 5 hours of NVG flight in a 24 hour period. To exceed that requires an extension approved by specific Command levels.
You are right, there is typically a disparity between fixed wing and rotary wing logbooks. NVG, terrain flight, and 40 lbs of body armor and assorted junk strapped to you make every hour that much more fatiguing. We can't hand it to "George", read the paper, and wake up at the initial aproach fix six hours later. (and yes, I know that you jet and Herc guys sometimes use NVGs) ;f
Each hour in a military helicopter pilot's logbook is dearly earned. (which makes M2 Carbine's logbook even that much more impressive. You don't run into many folks in his league) ;W