Why use watches or calculations to work out the drift when the DI/HSI can do it for you?
As others have said, you can work out max drift (drift angle at 90 degrees to wind) from MD=(windspeed x 60)/TAS.
In flight you can use the DI/HSI to visually gauge the drift.....
- Turn so hdg=trk, the MD vector is now at right angles to your trk.
- see where the wind direction is on the rose and drop a line (parallel to your hdg) from this point onto the MD vector.
- the drift is the fraction of the MD vector between the centre and where the dropped line touches it.
This all sounds complicated in words but it's very simple to use and takes less than 2 minutes to teach with a picture.