I cannot understand why it expires. I've heard it said that it's because some people do it then don't ride for ages but that sound like bollocks if you are over 24 you could do a DAS ride for a year then not ride for 20 and then jump on a 200hp sports bike. So I'm sure how jumping on a 125 when you are a bit rusty compares. The CBT pretty much covered what you do on a full test slalom, figure 8 , u turn , emergency stop and a monitored road ride to ensure you are safe. Most CBT are probably food delivery drivers these days and they probably put in loads of hours of riding and experience. Is be pissed off if I had to spring £120-150 every 2vyears just so could keep riding and keep my job.