What sort of relationship between WTSD and other stats should we be looking for? Or should WTSD be treated seperately?
I mostly ignore WTSD because it takes a long time to converge and I don't really know what I should be looking for even when it does. I mean, it's going to be different if they're LAG/TAG, it's also going to be off if they're betting their way to showdown frequently rather than just calling (I haven't actually paid close enough attention to know this, it's just assumption).
It's not my favorite stat. I use flop cbet/turn cbet to look for floating behaviors/two barrel opportunities (i.e., low fold to flop cbet/high fold to turn cbet) - in conjunction with those and AF, I use WTSD as a loose guideline of how much a cs the player is.
Like you say, WTSD can't be taken independently, takes a long time to converge (100's of hands at least), and a "normal" WTSD for an 18/15 is not "normal" for a 28/23 (worse, a 60/3 - for these guys, I'd have no idea how to interpret WTSD).
A possible line to address this problem (picked it up from a video I watched a few weeks ago) - people call too much at micro, it's the biggest exploitable leak at the very micro microstakes. So, you're pfr, you have position (much better to do this in position rather than oop) - cbet the flop relatively large, like 80% pot (barring board texture and villain specific considerations for the moment). We're expecting bad players to call flops alot, but to give up on the turn - charge them a lot to see the turn. Cbet the turn much smaller, something around 60% pot (again, barring board texture and villain specific considerations) - that should be enough to get them off alot of their hands.
So, if they're calling too much w 2nd pair type hands or A hi hands that they have to give up on the turn, we got the most out of them on the flop when they're making their mistake, and exposed ourselves to a smaller potential loss on the turn when the pot is bigger and when they have to fold.
But I understand OP's frustration to be the guys that absolutely won't give it up with any piece of the board or pocket pair. Once I figure out that someone won't give up, I shut down much earlier unimproved - out of position, I'll sometimes c/f the flop if I missed and the cs has position on me.
Just keep in mind that one of these times we will improve on the flop or turn - and we can valuetown the bajeezus out of them, cuz they won't fold that pair/draw/whatever. No matter how irritated I am by the cs that has position on me and won't fold to even three barrels w pocket 2's, I won't leave the table cuz I know he'll call me down when I hit a strong hand.