No – you can choose to attend only one of the three timeslots offered, either 9am, 6pm or 2am UK time.  It doesn’t need to be the same time every week, and you’re also allowed to attend more than one if you want. But you must be there live 80% of the weeks. As there are live webinars on 25 weeks, that means you must attend 20 of the live Tuesday slots over the entirety of CEC.