I'm pretty sure drakar was just using our old standby that you had one hour for the initial 'probe' which amounts to less than 1% of 5 day. Any more than that and you were considered to be conducting a 'system probe' for us and it burned the StMP for survey.
It isn't exactly spelled out in the rules so that was our 'rule of thumb'. A tactical probe was 1 hour or less and a system probe was greater than 1 hour. But it could be set to individual tastes.