I've enjoyed reading through what people here have said, and I've been in and out of the 33 since I got my power meter in 2017.
Yesterday was my first Cat 5 race: Grant's Tomb. My goals were to a) finish b) not be taken out by another ride, or, worse, take myself out. For b) I wanted to cruise through the hairpin on the north side at the front for the first two laps. I figured that by that time, the race would string out a little and the truly bad riders would be off the back. I could then settle into the peloton and get some protection until the end.
I wanted to start on the outside, cruise forward, attack on the first downhill, and go through the hairpin. This went a little too well, as I went off the front from the whistle, and it took two laps for the field to catch me. At that point, I moved back. Eventually, I wound up on the back of the peloton, which was about 20-30 racers of the 59 who started. I think it was a 12 lap race. About on lap 11, a rider 3 wheels ahead of me double-locked his wheels on the first 90 degree turn. The two wheels behind him did the same in response. Everyone saved. I went around them. I noted the wheel locker's jersey in case I wound up on his wheel later. On the final lap, I had burnt my matches and was off the back. On the final hairpin turn, that wheel locker was picking up his bike on the inside of the turn and there were two other riders on the outside off the course moving around him. I cruised through, happy to be off the back with the rubber side down. I learned from Strava later that there were a few crashes behind me on those first two laps. I'd rather finish tired and off the back than injured.
Overall, it was a ton of fun. I learned a ton of lessons about protection, using your power strategically, and having others do the work. The cornering lines were terrible for the most part, but I have done enough pacelining to be able to time this, so it was good to learn that my judgement on reading other wheels is OK. The race started early around freezing temps. My warmup could have been a lot better, and I'll pay more attention to that next time. I have a lot to learn, but I'll be back.
I raced cat 4/5 about a half hour later. There were a bunch of us who had raced the cat 5 race. I was on the waitlist and they couldn't find my number. When they did, I turned to the guy behind me and had him pin it on. I got to the line with 10 seconds to spare, so I was at the back. We then rolled out. I took the hairpin and moved up on the inside. For the first two laps, I just kept moving up. I wanted to get up with the 4's who hadn't raced and sit in the peloton. Eventually, there was a group of about 5 of us 20 seconds behind. One guy marshalled us into a paceline to chase. We almost caught the peloton, but shortly thereafter I cramped on my right calf. I tried to recruit other muscles, changing my foot position. It slowly wore off. Then my left leg cramped. At this point, I was looking to be pulled. I went another lap, and a marshall pulled me out. 10 of 16 laps completed. Being pulled out was the most merciful thing done to me in the past week. Still, I had finished ahead of about 20 or so riders who were pulled ahead of me, so not too shabby.
Again, there were more lessons learned from that race. Between races, I should have kept working my legs to get any recovery I could. My fitness is good, but my tactics are bad. I'll get those honed.