I used these mid last year for a largish tiling job on a not particularly even floor and they worked great, but yes use a decent bed of adhesive and when you put the bed down, scrape away the adhesive about an inch back from the edge where the tile set goes.
Watch a few YT's and you'll be fine, but I do highly recommend you get a proper setting tool for the wedge for even pressure, and spend the time making sure the first line is all good, level and running in the right direction if you need a slight runoff.
If you're not sure, you can always put down the first line of tiles, place the tile leveller spacers in place then let it go off for a few hours so when you do the next lines after the first properly set line of tiles won't move when you do the wedges for all the rest. Do make sure you place the leveller spacers BEFORE the adhesive goes off, as trying to dig out a space for it under the tile edge after the fact is a PITA, yes you can infer I know this from experience
Far as professionals not using them that's pinapple. LOTS use them, it's bloody simple and a LOT quicker than tapping and feeling for edges.