The concept of recent is relative to what is being discussed.
I have been cleaning the dishes
implies sometime today, probably within the last hour or so. Why? Because cleaning the dishes is an almost daily occurrence in most households.
I have been studying for the bar exam
implies that you are not studying now. It does not imply that you have been studying today or that you will not be studying again tomorrow. It implies that you have been doing so for some unspecified period, probably days or weeks or perhaps even one or two months. It does not imply that you stopped twenty years ago when you passed the bar exam.
There is no rule based purely on measures of physical time. Language is a social construct and relates to the social context of what is being discussed. So "recent" varies with what is being discussed.
In the case discussed by Lambie in the comments, she seems to assert that, so long as the condition caused by the action specified by the verb continues, the event remains "recent." I cannot wholly subscribe to that assertion if she even intended it. It is too extreme and relates only where causation is implicit or explicit..
I think, however, it is perfectly valid in the context in which it was made.
I have been washing all the outdoor furniture and am so tired
is proper and does not indicate with temporal precision when the washing stopped, but it does imply that the washing caused the current tiredness and so must have ended after the previous time that the speaker experienced tiredness. But this point about the continuing nature of the condition caused is not absolute (nor, to be fair, did Lambie explicitly say that it was absolute).
The U.S. government has been working to free Europe from German occupation
would have been a sensible thing to write in 1946, but it is ridiculous to write in 2020 even though Europe remains free from all German occupation (except tourists).
I think you need to take Lambie's point about whether the condition caused is continuing at the time of speaking as helping to define what is recent without fully determining it.
In short, recency is relative and determined by social and human considerations rather than by a clock or a calendar. Moreover, any ambiguity can be resolved by inserting an explicit time marker.
I was washing the outdoor furniture until an hour ago and am just so tired out.