Personally, I hate those things.
Not because they don't do an adequate job (they're okay), but because the diamond stones are always an odd size and only their replacement stones fit.
Buy a dedicated angle guide that you can use with any size of stone, worth it in the long run
That's half my problem. I can't find definitely how my board was setup from the factory, but the place I bought it from said most of the time these intermediate all mountain boards are setup with 1 degree base and 1 degree side.
Very hard finding tools that are reviewed that accept stones that seem to be typical. Very hard indeed finding out the 'proper' procedure to do things. The link posted on this site is even wrong from what I've read. Or I should say, extremely glossed over.
Now I'm reading about sidecuts. You are supposed to have a sidewall tool that cuts the side of the board down to allow the shaving of the side edge O.O
There is one tool that does all of this, but users have reported some issues with it be exact throughout the entire edge.
Most sites just show you to use a file guide, a bastard file, and to make passes down the line. MOST sites however, show the person to go over it more than a couple times. Which is bad from what I've read. That's taking way too much edge off. Next, they jump right to using a gummy stone. Sure you COULD do this but, it's def not the proper way by any stroke of the imagination. Every video I have seen has something I read that I SHOULDNT do in it. So I dont know what to believe.
I used to hand sharpen my skis years ago. I used a file, a few passes and a piece of tape on the file to keep from scratching the board and to add about a .5 degree bevel. I used the sharpie trick 10 years ago. Works well, and really lets you know if you have edge problems or , aren't getting an even tune.
Seems like the set degree tools with a large surface for grabbing onto the board and glidding down are the best. But many of them use specialized stones.
There is a proper way to do all of this, and most of it is in written form. There are variations of the proper way, but as of yet, I have found no videos to demonstrate this that even closely matches.