PAF has older jets so made sense to have more per squadron. Newer jets should have better availability.
If we have ordered 20 J-10s as the leaks suggest then it will be one operational sqn and a few jets with ccs/ace.
More jets in a squadrons has also to do with the serviceability rate of a squadron due to reduced MTBO (Mean Time Between Overhaul) of engines leading to requirement of overhauling....
To an air force, the number of squadrons is not the relevant consideration as much as the total aircraft available. A squadron of 16, if no additional aircraft are available for maintenance and attrition, is a different proposition from a squadron of 16 backed up by 8 to 10 additional aircraft.
Pakistan had, at times, had as many as 24 F-6s per squadron. But the aircraft had to undergo major overhauls after 600 hours of flying, and its engine had a Time Between Overhaul of 100 hours. Sometimes, PAF had less than 12 ready aircraft per squadron despite the availability of twice as many.