Perhaps so Blue, but on the other hand, brigades with low call rates may have trouble keeping their members interested & enthusiastic. It is very difficult to keep new people enthused, when they join up, and then don't get to go to a call of any type in six months or more.
There is also an aspect of keeping people's skill levels up...while you do lots & lots of training which is aimed at maintaining skills, you also want to get to practice some of those skills for real (and throw in some adrenaline, and people may react differently to what they do in training) - so an opportunity to try those skills for real is good.
I know what number of calls ideally suit my brigade - in term of keeping the interested, attracting new members, not putting too much strain on the existing members...we did 61 calls one year, and it was just right for us....but we have much lower call rates for the rest of time......
Pip