Following Richard's lead, I trot out this sort of stuff every year or so, on demand, whether they like it or not!
I went a little way down the modern sharpening path some years back and had various jigs (the cheap ones) 3 EZE lap plates, Sorby Proedge, etc. Then one day I was absent mindedly poking a chisel over an oil stone and suddenly discovered that freehand was faster, easier, and could be as sharp as you wanted. Never turned back!
Sold the diamond plates and the Proedge. Still got jigs in a drawer but haven't used them in years.
Amongst other things, three essentials with freehand sharpening on oil stones;
1 you need to freshen the surface occasionally; I use a 3m diapad which I happened to have, but any old bit of stone will probably do
2 You need to put some energy into it, which is much easier if you dip as you go, creating a slightly rounded bevel, which as we know is anathema to modern sharpeners, for no apparent reason. Start the pass at 30º then lower it a touch, fast and energetically
3 Bring up a burr
along the whole edge, especially near the middle of plane blades as this is where you get most most wear, Then turn it face down and remove it.
4 Ignore all the frantic borlocks about flattening/polishing everything.
PS I don't use a powered grindstone at all. Cause problems for novices, easily avoided, blades last much longer. A little and often sharpening will keep it in good shape.