At what point does next Tuesday mean
the next Tuesday that will come to pass
and no longer
the Tuesday after the Tuesday that will come to pass?
And, when does the meaning switch back?
To me, “next Tuesday” means the Tuesday that comes next week. For example, on Monday, October 11 and Wednesday, October 13, “next Tuesday” means October 19. Whereas on Monday, October 18, “next Tuesday” means October 26. “This Tuesday” refers to the Tuesday that comes this week, which on Wednesday would refer to yesterday, and on Monday refers to tomorrow. Similarly, “Last Tuesday” is the Tuesday that came last week. Without any descriptors, day names by themselves mean the next such day in the future unless used in the past tense. “He will do it on Tuesday” means the next time there is a Tuesday, which on Monday would mean “tomorrow” but on Wednesday would mean the following Tuesday. In the past tense, day names mean the last such day which occurred. “He did it on Tuesday” means the most recent day that was a Tuesday.
Not everyone may agree with this analysis, but in my experience this is what most people mean when they use “this”, “last”, and “next” with day names.