"Have you visited him often?"
"For the last six months I've driven up to B. quite often."
"For the last six months I've been driving up to B. quite often."
The rule I have is that the present perfect simple is used when talking about "how often or how many" and the present perfect continuous is used when emphasizing "how long"— that is, the duration of an action.
If I go with my gut feeling, I would choose the present perfect simple.
But "six months" is a length of time, so one could argue that the present perfect continuous is also possible here.
Can both be used here depending on the perspective of the speaker?