Thanks for the insights. I guess the few instances I found where people have mentioned 'hall-hopping' as possible are out of date or it's not the full story.

Of course, complaining about the differences in the BC lounges in 2E is the epitome of '1st world problems'. Then again, what is being charged for full-fare BC nowadays is certainly 1st world money. I have had opportunity to visit the Hall K lounge several times, an in each case it has been less than stellar - dark, worn, cramped and over-crowded, shortage of charging points, entirely insufficient and poorly maintained bathroom facilities for the number of people. My single experience with the L lounge was night and day difference. So if the opportunity had been available to rather layover there, I would have taken it.