If it is not practical for an open site inspection I have no problem on sight wells. This is a case by case basis. If there critcal issues with like bedding or compacting then sight well may not be the way to go. Same applies with the number of wells.
As far as where they would shound be placed, I would recommend above the buried conduit(s). If they were on the side or underneath the conduit, it would sort of be a mute point.
All kidding aside, It is all a case by case basis. I think there are too many varibles to figure on to give a rule of thumb answer.
