I think, its not diagonal always, and depends on the drive type; like FWD, RWD, AWD, 4WD, etc. All of these have different patterns, like Forward cross, rearward cross, X-Pattern, etc. so must be chosen accordingly.
Generally, for FWD, Forward cross is adapted, and for RWD, AWD, rearward cross or X-pattern are adapted.
I think, instead of opportunity, they must be fully followed after prescribed time interval, which I think is 10,000 Kms, in case of FAW V2.