I'm not a table mechanic (my preface to most posts here :wink

....
I hate wax. It has a tendency to rise up out of the seam. This causes a bump. It also sticks to the cloth, ruining it. This happened on my table and other tables I've seen.
I think the only way wax could be used would be to:
1. Guarantee the table is in a very tightly climate controlled environment. This means very minimal temperature and humidity fluctuations.
2. Glue or lock down the slates in such a way as to keep them from shifting in any axis, side to side, up/down, in and out.
3. Apply the way as sparingly as possible, minimizing how much gets on the playing surface. No matter how well you razor scrape the wax, there's still a layer on the playing surface. Aside from that, I don't think it's a good idea to get a lot down in the seam, as that makes it easier for it to ooze out if the seam changes.
The first time I set up my table, I used wax. Big mistake. A lot can go wrong with wax. This time I'm going to go Bondo. Will eliminate a lot of problems.
Getting the wax off was a big pain in the butt. Blow torch and scotchbrite pads and lots of elbow grease was the only way. Chemicals didn't work. Have to use too much of them, and it still leaves wax in the "grain/pores" of the slate.
Wax just seems to me to be a super quick and easy way to fill seams in a "good enough" kind of way. Vastly quicker and easier than other methods. Rather than the ideal way that is less susceptible to problems.
I set up my table on concrete floor that has ceramic tile. No issues there. Friend of mine did the smart thing, we put his slate on and then left the table alone for a little over a week. This allowed the carpet to get fully compressed. He (his wife) didn't want to cut the carpet, so this was the next best thing.
Sounds like a fuss, but it actually saves time I think. Level the table on fresh install on thick carpet, and you'll end up having to do it all again once the table sinks in. Rather do it once, than twice.
Don't know how you table mechanics deal with that sort of thing, doesn't seem practical to allow it to settle.