Definitely case by case. I was told all along by my recruiter I'd be doing TaRC course then 2 weeks before my start date he informed me I'd actually be doing full 10 weeks basic!
Tbh even as a rejoiner and having to do full 10 weeks it wasn't that bad. Instructors knew my background so often left me to my own devices outside of the compulsory bits. It goes quickly and you'll find it 10 x easier than Army basic, i know I did.