Diversions as a student
 

I'm finding I make silly mistakes when being given a diversion on a nav ex using approximations like max drift. In contrast, I'm at ease doing a whiz wheel calculation (having a wind arm helps because one doesn't have to mess around with the iterative method and I can do it with one hand). So, is there any reason not to simply use that in the cockpit?

I would never mess around with a whizz wheel or any other similar tool in the cockpit. Get the wind arrows marked on your map along with max drift. Make yourself a circle on a piece of paper and divide the circle in 4 slices with two lines. Mark the slice lines with

15deg= 1/4
30deg = 1/2
45deg=3/4
60deg= Full

This estimations is all you need for diversions.

I do things even more simple. Wind from the left = 5 degrees correction to the left and vice versa. Regardless of actual crosswind component or wind speed.

What you need to realize is that when doing a diversion, you're not going to do that using dead reckoning. Instead, you're going to ask ATC for vectors, use radio navigation or feature crawl. All offer plenty opportunity to correct the initial guesstimate of 5 degrees.

Likewise, my thumb is 10 miles which equals five minutes. 4.5 minutes for a tail wind, 5.5 minutes for a head wind, regardless of strength. Revise halfway through the diversion as required.

Construct yourself a wind star during your pre flight planning. Draw the lines to make 8 points of the compass (N, NE, E, SE etc) and then write down the drift and the ground speed for each direction. During a diversion you can easily just look down and see the drift you would expect. For headings that are in between these eight points, then go for a drift and ground speed between the values you have written down.

PPPPPP

I loved practising diversions during my PPL training!