I’ll start this thread and hopefully more people will add different experiences.
This is for all kind of visual prediction.
I’ll start with VB2.
VB2 needs reference time if it is played without timer it can be unstable. For example if reference time is 1.5 sec with some practice it can be relatively accurately counted. On a newer wheel there may be requirement for time of more than 2 seconds. Counting 2-3s time period with reasonable accuracy is very questionable. 200ms difference when timing the ball may give you about 10 pockets error. If you use same counting for rotor for example 2 sec is only ½ rotors rotation, so on a full rotor revolution that would be 400ms difference. Such difference may make additional 10 pockets error. VB2 reference time if it is longer than 2 seconds shouldn’t be counted! Even for rotor is better to use a metronome set to 1 sec. then use 2 or 4 seconds to time the rotor with greater accuracy.