ratrat,
you mantioned " they didnot care (to) ...calculate physical persence..."
As I understand calculation of physical presence is relevant at the time of filing N 400. After that one can travel out of US but has to atleast maintain his LPR status. If, by staying away he looses his LPR status ( so determined by the officer at the POE) , then he looses his GC and then naturally his N 400 cannot be processed.
However I would not know what will happen if at the time of interview the officer finds or concludes that one has lost his ties to US and lost his LPR status in the process. Would he still process his N 400? I would think if he is away for more than 6 months the interviewing officer may conclude that there is a break in his LPR status, and decide not to process his N 400.
Similarlly, during staying away from US between interview and oath one should be required to maintain his LPR status. So calculation of physical presence is not so much relevant.
Above is my understanding. I would like views from gurus like JoeF, 2B1citizen, chicadodesi, cornerstone, shaky , Jitender , mariahoney and others.. please !!!