Yeh, just do one and see – they’re only awful if you make yourself go full-on. (and, of course, you will 😀 )
If you use the mobile link app you can see the evening before how many riders have already signed up for each event. IME big fields mean that you’re unlikely to win anything but way more likely to find riders close to your own level so you’ll get a meaningful race rather than a short group ride followed by a solo TT
check things beforehand – drink, towels, fan on full blast but also that you’re not riding a TT bike, as that’d get you a DQ in most road races (maybe you never use it anyway – I like to if I’m doing a steady ride as it removes the drafting effect)