Exactly this! I have been to every Disney theme park multiple times in both their highest and slowest seasons (exception of Shanghai as I only been once so far) and its amazing how the dynamic basically stays the same at all these parks worldwide. But its usually the same, get there at opening, get in lines for the biggest stuff first or FP it later and you will ride and see pretty much everything you want within reason. Yes you won't be able to get a FP for everything and some rides you may have to wait an hour in but thats why you either ride the biggest ones first or get a FP right away. And thanks to Maxpass, its even easier now because you can FP from both parks with your phone.
Old people like me remember waaaaaaaaaay back in the 90s when FPs didn't exist. You didn't have ride wait times in real time at your fingertips so you could actively strategist what to ride next. There wasn't 100 websites giving you suggestions when was the best time to visit or best time to ride so and so ride. Or message boards like this one where you have tons of Disney nerds giving you tips to plan your trip better. Most people use to just show at the park and figured it out as they went. And if they went on a really busy day, they were screwed.
Nobody likes being in a busy park, but going to any of these parks are really SO much easier today because you have so many tools to help you with.
One of my favorite Disneyland stories (and I have a lot of them) is from the 90's...I was 23 years old, fresh out of college, waiting tables, living in North Hollywood. Disneyland was a treat. Went there maybe once or twice a year. Anyway, I'm there with my college roommates, there's no such thing as Fastpass, you had to strategize. It's towards the end of the night, we're plowing through as many rides as we possibly can. We're knocking out the dark rides in Fantasyland, we get in line for Mr. Toad's Wild Ride. Exhausted father with his kids is walking ahead of us, sees the line for it (not a ton of people, but slow loader), and so even though it's not a giant line, you know it's gonna be about 20-30 minutes. The dad grumbles under his breath but we all hear it: "All right. Let's go do this Toad sucking thing." We laughed our off. (Can I say on WDWMagic? Guess I'm about to find out.)
EDIT
Apparently not.
Anyway, we still quote that dad to this day. So, now, with all the options to beat the grueling slog of long lines, and all the information on-line and resources from authors about how to make the park work for you, rather than you fighting the park -- I really just stare in amazement at people who stand in long lines at Disneyland or California Adventure or Animal Kingdom or damn near anything. Just do the work beforehand, and roll with what happens. Went with my wife just a few years back (before the MagicBands or Magic My Way or whatever phone apps kicked in). It was July 4th weekend. Day after the 4th of July, I knew it was going to get insane (so I set expectations accordingly) -- but we showed up early, were on Main Street before Rope Drop, went straight to Peter Pan's Flight (it's my wife's favorite, that's another story). So it went like this...on July 4th weekend.
Peter Pan's Flight. Dumbo. Matterhorn. Jungle Cruise. Indiana Jones. Pirates. Haunted Mansion. Splash Mountain. Tom Sawyer's Island to dry off. Winnie-the-Pooh. Lunch at Blue Bayou. It was noon and we had knocked out almost everything in that side of the park. So by this time, the horde has descended. So Tiki Room. Tarzan. Root Beer floats at the Golden Horseshoe. Fastpassed stuff while hitting fast-loaders. If we saw a long line for, say, Buzz Lightyear, we certainly didn't stand in it, we fastpassed it and went and did something else. You have to show up early, stay late, and use the Fastpass system with some strategy. Don't fight the park. Work with it.
Oh, one more tip. When "the horde" exits at the end of the night...do not get into that giant assembly of humanity walking to the transportation to parking. Just don't. Don't do it. Kick back, relax, have some ice cream, let all those people get out of the place. Disneyland keeps Main Street stores open late, so while attractions may close, it's very, very cool to walk around the place with someone you love, largely alone, and the bus trams run late to accommodate late shoppers, so that's an easy and relaxing way to avoid maybe the most hardest line of all...the horde waiting for the trams back to their cars. Don't do it.