To be honest I was never allowed to use the whizz wheel in both commercial and IR training and haven't had to use it since unless PPL instructing.
I got taught to work out your max drift and then use the clock factoring to work out your drift then use percentages to work out the GS.
In the air I mostly use the 1 in 60 rule.
And some PPL's are actually very switched on with DR and would put some commercials to shame. Its a perishable skill though and if its not exercised you will make stupid mistakes. Which is why I prefer to exercise my mind then check it against the GPS and if they disagree I check both again. The rare times they don't agree its a 50/50 between me getting my lefts and right muddled and the gps being pointed towards somewhere in the middle of china.
Oh and I have twice avoided busting airspace by having the NAV radios setup when a map update had a VOR offset from its proper position.