Does anyone - even Zwift employees - know whether there are any differences whether one calibrate the Kickr in Zwift or use the wahoo app to calibrate?
Is the advance spin down in the Wahoo app even more accurate???..
If you try both and cannot tell a difference, does it even matter? You have tried both??
Best to use the Kickr app, imo. Do you have a wheel on or direct drive Kickr?
If it’s wheel on, you will want to increase your tension so the spin down time is in between 10-15 seconds for accuracy. If it’s higher, tension too loose, less too tight.
Advance spin down only needs to be done once in a while. It’s more for first time set up.
You only need to do spin down once a week or if something changes, like removing the bike and tension.
I just marked my Kickr knob and turn it 2 full and 3/4 and it always ends up at 13 seconds. No slip.
That is if you have a Snap. If not, disregard this rant. 
Kickr Gen 3. Thank god i splurged on the direct drive. I’m obsessive with these accuracy thing and I would not have been satisfied with the wheel-on. There would have been too much mucking around.