present perfect in "since sentences"

Hello all!

I´ve found almost perfect post explaining this phenomenon however there is one thing I don´t quite understand. First, please look at the post so that you understand what I mean:

With the expression "it's been (length of time) since..." as in

1) It's been a long time since I've swung a golf club

2) It's been a long time since I've been to Augusta

...the present perfect implies that the action is something that is repeatable. The speaker has probably swung a golf club or been to Augusta more than once.

3) It's been a long time since I swung (not *swang) a golf club. 4) It's been a long time since I went to Augusta.

With a verb phrase that could be a repeatable action, the simple past (swung, went) could indicate a single event. The speaker in 3 may have swung a golf club more than once, but could also have done so only once. Similarly, with 4, "went to Augusta," the speaker could have gone there many times or only once.

For example, one would say It's been a long time since they cut down (not *have cut down) the old oak tree, but I still miss it With verbs that denote a single, non-repeatable action, the present perfect is less natural. It would be odd to say:

-It's been a long time since they've built their house.

-It's been six years since I've moved to this apartment.

-It's been two years since my dog has died.


I perfectly understand why I can not say these three sentences. Unfortunately I fail to understand the sentences 1 and 2 - their second part, to be more exact. It is explained the way that "The speaker in 3 may have swung a golf club more than once, but could also have done so only once." That´s the issue.The way I get it is that the first part of the sentence "It's been a long time since" says that it has been a long time since the one e.g. event in the past. From that standpoint it would not make sense to me to look at it the way that "The speaker in 3 may have swung a golf club more than once" - I would not on which of my "swings" "It has been a long time" is pointing out.

Thank you!