If you are GM’ing, just call it when you feel like it 🙂
I don’t often use spotting rules except at the beginning of a scenario or if we’re playing in pretty dense terrain, partially because my kid and wife both get frustrated if they “can’t see the guy” even though he’s right there 🙂
Long explanations of “the empty battlefield” tends to meet with “Well, that’s stupid”.
You run pretty pulpy battles, so I probably wouldn’t unless one of the players said they were going to sneak up at the start.
If its the VC vs the Yanks in NAM, then I’d enforce spotting rigidly.
On the down side it gets harder to spot somebody the ‘further’ they are into a piece of cover… don’t really get that one?
The thought is that the further you are into the terrain, the more branches, rubble and shadow is in the way, so it’s harder to see the exact position.
As a final thought, one playtester suggested that if the guy has already shot at you but you fail the spot roll, you still know roughly where he is, you just don’t have a clear shot, so let the player shoot but require a 10+ to hit.
Some players will ALWAYS take that shot, others will figure they should be moving to outflank instead.
Hope that helps!
Nordic Weasel Games