Agree wholeheartedly that the time adjacent to obvious planned fixes every 6-10 min is the best way to correct timing. There will be those who, having found they are off track, decide to go direct to destination rather than regaining the planned track - such as the chap who recently blundered into a busy CTR by 'cutting the corner' in such a way!! It's quite likely that many GA GPS users also take the easy option of selecting 'Direct To' rather than correcting XTK after discovering track errors - and this could also easily result in unplanned penetration!! Even if it does save the few pennies that some would allege are apparently so essential to them!!