Something else to consider is the experience level that squadrons need to maintain. There needs to be healthy mix in every squadron of senior pilots with loads of quals under their belt, newer pilots fresh from the FRS, and everything in between. Otherwise, you eventually end up with a problem. If all your experienced pilots are getting out, it doesn't matter how many fresh 25 year olds you can shove through the flight school pipeline.
OldRetSWO is also right. Flight hours go up and down based on the health of the aircraft within a squadron, money for gas and maintenance, etc. There needs to be some continuity of regular flying to stay sharp, but it takes several years to produce a pilot who is barely qualified for combat. You can't suddenly decide to turn on the spigot when we go to war in Syria, with China, or with North Korea. You go with who you have.