I think its easier just to do it on the dg (or even an obs if your dg
has failed and is covered up)-- as
Gardner said, count 10 seconds per "numbered" heading, even if it
means putting your finger physically on the
numbers as you count from your current heading to your desired
heading...

Yeah, that works great unless you have a barrel DG (or the DG is
covered) and an indicator without full view of the numbers. I've flown
IFR in such planes.

Michael