Tests for Leaky Cylinders

Has anyone ever used compressed air to test for a leaky cylinder? I was given a "Motors Auto Repair Manual 1956" and it covers Willys Jeeps as well as lots of American cars of that time. But right at the back it has a section for testing leaky cylinders and valves. It goes like this;
Remove the porcelain from an old spark plug and braze a tire valve into the shell.
Bring No.1 piston up to top dead center on the compression stroke.
Screw the modified plug into the spark plug hole
Apply air pressure and then listen for the hiss
At the exhaust for a leaking exhaust valve
At the air cleaner for a leaking inlet valve
At the oil filler for leaking rings
Remove the radiator cap and look for bubbles which will indicate a leaking cylinder head gasket.
And then do each piston the same way.
I thought that it was a handy way of testing

I've done it, it works. It can be a handy-dandy troubleshooting tool! You just have to be sure that the piston/crankshaft is at dead-nuts TDC or the air pressure will push the piston back down, and be sure that the old junk pile spark plug base you use doesn't have too long of a reach or a bent valve can result when the engine spins from the from not being at exactly TDC..... Don't ask me how I know.....

There is a leak down test tool with a built in gauge designed just for this.  As you mentioned, it's a quick way to determine the health of each cylinder.  Here is the cheapy I picked up at HF...

Bruce W wrote: When you have the piston at ( or as near as possible to ) TDC, put the transmission in high gear and set the parking brake. This might keep the piston from moving. BW

Why didn't I think of that