Except I'd expect the squadron leaders were all ace pilots like Focker instead of raw recruits with a talent for getting shot down like Kakizaki.
Attrition on the 30 1Ses should've been a LOT slower than, say, the brown 1As that they stuffed full of raw recruits with no flight experience, much less combat experience.
If, say, 1 in 10 valks destroyed is a squad commander, than by the time the last 1S goes up in smoke, they're OUT of valkyries. Completely.
If 1 in 5 is a squad commander, then they're down to 62 valks TOTAL by the time the last 1S goes up.
It's a very simple equation, really.
182-30X = # ovf valks remaining after all 1Ses are destroyed, assuming no new ones are made or acquired.
182 = 212-XM = all non-1Ses on the Macross.
M = # of non-1Ses destroyed for every 1S. X = # of 1Ses destroyed.
Once you drop below about 1 in 4, you have a reasonable # of valks left over after complete 1S destruction.
But the ratio shouldn't be that bad to begin with.