That sounds hideous. I can entirely imagine it. I remember once going to Legoland for the fireworks event and it took an hour and 20 minutes to get out of the car park (i think they did something different in subsequent years as people complained so much - kids who needed the loo, freezing in our cars, nowhere yo buy a coffee etc)
I think it is worse since lockdown. We have only ever enjoyed Merlin parks when we bought passes. We chose a year, got them with Tesco vouchers, and then did the parks so many times i lost count (we lived between Chessington and Legoland at the time).
I genuinely feel sorry for people who pay for a day pass on a peak day. It is exhausting and so disappointing. With a pass there is no stress or pressure - you can pop into Legoland to use the play areas and always catch a last big ride in the "join a queue 5.59pm and ride when the park closes".
We did Chessington after covid ended without passes and i felt very ripped off. The kids had fun but as an adult i found keeping them happy in long queues very stressful.
Merlin won't improve the experience while people are prepared to pay for it. And they will pay and pay.
I honestly think it is only worthwhile to do peak days or special events if you have a Merlin pass. Otherwise only go on a school day - plan to go on a school inset day, it is your best bet.