There are things you can do to speed up both marking out whilst increasing accuracy, and increase the strength of the joint when using medium slip setting (on only one side of the joint)
Use a rod board for marking, no measuring required. Just cut a bit of offcut the same size as whatever face you intend to join. Or reference off side plate of machine, or in some instances make a little template from offcut (the same as if you were installing shelves in a carcasse and screwing/glueing them in) but instead you could ref the side plate of the machine against that. Or if installing shelves or centre divides, run the machine at 90 degrees to the work, with the base plate referencing off it. Again rod board for marking.
With regards sloppy settings - I tend to use medium slop one side, particularly on sheet goods. When learning mortise and tenon joinery cut by hand, my instructor (who was brilliant) said that some vertical slop is acceptable and even sometimes preferable, as long as the cheeks of the tenon were a good fit. This is due to during glue ups, a bit of wiggle can help if you need to pull one way on the clamps to avoid rack etc, particularly with people who aren’t cutting tenons by hand every week.. this still produces a very strong joint. Glue area is sufficient, and the shoulders of the tenon actually provide most of the strength really, so if they are good.. Also how the joint is usually employed, it is needed for most alignment and strength in this orientation.
If concerned use pu glue, jowat is the best I have used. Tape off the joint though with plasticy tape first as it fizzes out and is a bigger to clean off !
Even with all the above considered, the domino should be considered a pretty decent alignment tool that is a quick option, I wouldn’t personally use it for anything requiring massive strength (but for drawers, cabinet doors, face frames, stretchers or rails on cabinetry but probably not dining tables, carcassing etc it should work fine)
Setting up a morticer accurately takes a fairly long time. Even in a workshop with decent kit, as the morticer tends to gather dust most of the time and needs a lot of work. As does cutting tenons. Not to discount them, just saying
Also incidentally whilst I’m a full time cabinetmaker, in my work life, in my home workshop I don’t have a festool, wouldn’t buy one of the router jig thingies and I use a cheap Chinese dowelmax knock off. I would possibly consider the Peter Millard domino jig, but haven’t had any real need for it tbh.
Anyway my thoughts