Every position after the first few moves of the opening requires a certain minimum level of tactical attention. Even in a quiet position the first questions you should ask your self after your opponent has moved are:
- "What is my opponent now threatening?" and
- "What is my opponent trying to achieve with that last move?"
These questions can have both tactical and positional answers and they can have more than one answer. Asking these questions is what Nimzowitsch called "prophylaxis" and it is what separates bad players from good players.
Positions where there is tension, where captures on both sides are possible always require some calculation if only to decide whether it is a good idea to resolve the tension. It is particularly important to keep an eye out for tricky little zwischenzugs and by both sides. Again, both material and positional factors need to be considered in evaluating the position after the dust of exchanges has settled.