How do you know which tense to use? Does the usual rule about a ‘beginning and end’ apply?

Hola Claire,

With modal verbs this rule is slightly different. In these cases that the action had a clear beginning or an end is not noticeable.If I say: "Pudiste/Podías/Podrías haberme llamado para hablar", (You could have called me to talk) for example, the three options are referring to something the person could have done (but he/she didn't).

We could say it is a question of style. 

Inma