Beware of the example with prefix по-

Since it's NOT a directional prefix, one might get a wrong understanding and a wrong idea about this concept.

Once you add a directional prefix to a verb of motion, you are no longer make a distinction between multidirectional and unidirectional motion. The direction of the motion has now been determined.

ходить(imperf) - приходить( imperf)//   Идти ( imperf)- прийти( perf)  

As a result, the indeterminate verb in the original pair will become imperfective, and the determinate will become perfective.

With non-directional meaning of prefixes though it's not the case.

ходить( imperf) - походить(perf)

That's why the example given in this article with prefix ПО- is incorrect.

One can't say " Кто- то по ней походил, а потом уходил в лес."

It should be ' Кто - то по ней походил, а потом ушёл в лес"

Just like when you express sequence of action  Мы послушали музыку, поговорили и ушли, using perfectives