It’s all personal preference. Some people really benefit from a lot of before hand practice, some don’t need any and do really well, then there’s the remainder who can practice all they want and still come unstuck.
It’s all about coordination, and the ability to concentrate whilst operating at speed. Unfortunately not everyone has that level of coordination, people really put pressure on themselves to pass these test, it’s my genuine belief that you can either do them or you can’t.
You have three people on those assessment days; those that can’t, those that can, and those that can do it really well.
The amount of time you get between knowing you’re going for the assessments and actually going is so narrow, that you can’t possibly build the required coordination to pass.
That’s why I believe you’re best option is to practice to the point that you understand each assessment, but don’t drive yourself crazy over them.
If being a driver is something you really aspire too, then I think it’s worth practicing what’s required of you even before you’ve applied. If you’re sat their waiting for a job advert to pop up. Then I recommend you start developing your coordination, work on your memory and all the other sensory skills that you require to pass the assessments, because as I’ve said above, either you have it or you don’t, so your best chance is to start developing as early as you can.