The concept was weapon/target matching.
If you had, say, 60 F4 available and each had 8 missiles that was 480 missiles.
If each kill was assumed to require 2 missiles then each aircraft could take out 4 targets. There would be some attrition but that meant that the spare ship-set for aircraft one could be shared with aircraft 2 and 3 etc.
If the enemy was assumed to have only 200 aircraft to attack the Uk then it would follow that we had enough weapons.
A similar issue was used for the Nimrod. UK ASW Force had 38 Nimron initially and only 300 torpedos - 200 x Mk 44 and 100 x Mk 30 = 50 ship sets. Same logic.
The V-Force had one WE177 each (approximately)