As gurn previously stated, the Germans couldn't have rotated their crews in the manner you propose since doing so would have necessarily required the training of more aircrews, which in view of the tight fuel situation wasn't practicable unless the Germans were willing to significantly reduce training duration (and thus individual fuel consumption) to churn out more, albeit worse, pilots.In that case it is a strategy for defeat .
in case of a war of attrition it better to have 10,000 aircraft performing 500,000 sorties than 5,000 doing the same .
the number of combat missions each crew has to take is halved , increasing their chances of survival on the long run.
also the individual air-frames themselves are subjected to less stress and wear.
The Soviets actually applied this model during the war, and their results, despite having more aircrews than the Germans (and thus, presumably, better rested aircrews), were actually worse than the results obtained by the "inefficient" German approach - they got shot down in droves, and it took them about three years and the exhaustion of the Luftwaffe in the West to attain something approaching air superiority over the Eastern Front.
Regarding the wear and tear of the airframes, this is truer to some extent, but again this forgets that the Germans systematically produced way more aircraft than they lost - therefore they could roughly replace, on a yearly basis, their original complement with the latest models. Take Williamson Murray's Strategy for Defeat. In Table XVII, he gives the total German write-offs for 1941 (excluding November for want of data). Here is the data, in proportion of the total German production:
1-engine bombers: 366 / 476 = 77%
X-engine bombers: 1,798 / 3,874 = 46%
1-engine fighters: 1,327 / 2,852 = 47%
2-engine fighters: 463 / 880 = 53%
Admittedly the true total is higher, not only because of the losses sustained in November but also because a portion of the damaged aircraft were probably retired / cannibalized / never repaired. Nonetheless, with the exception of the Stukas it is evident that the German production level was sufficient not only to cover losses but also to "modernize" the front-line units of the Luftwaffe. This is even truer when you take into account that losses in themselves contributed to the "weeding out" of the old planes.
