[Fantam]

I think it all depends on how big the pot has become, how many other players are still in the hand and how straightforward you think the better/raiser plays. Another possible consideration is how many overcards could fall to beat your top pair.

For example if I had top pair with say JTs in a small pot with many opponents and a normally passive player raised or check-raised me on a 3 flush board on the turn, I would seriously consider folding.

However with the same hand and board, if someone that I thought was loose and agressive raised or check-raised me on the turn HU in a very big pot, then I would most likely call down.

Where you draw the line is down to your judgement. However, I must admit that its not often that I would feel comfortable continuing with top pair when someone had raised me with a possible made flush on the turn at micro-stakes.

Editing: And if I was in EP, I would usually bet the turn with top pair (particularly TPGK). Unless perhaps I had a vulnerable hand like say A7s in a multiway pot and I had paired my 7.