I think if you were going for only 2 to 3 days, anxiety to get it all in and have a good time would be near impossible to combat. This is how I feel at WDW because there's so much to do, so many parks to visit, and getting to and from your hotel to parks is so time consuming.
I don't feel the same anxiety at
Disneyland. You can be an under 10 minute walk to the gate if you choose. You can walk across the courtyard to go from one park to the next. It's an infinitely more walkable theme park. The sun can be a factor but it's not oppressive like Florida heat is.
I think the best idea going into the trip is to realize it won't be perfect but to have a plan to accomplish what you'd like to. Know that your best laid plans may not happen and be flexible. I think 5 days is plenty and will give you plenty of flexibility to have a great time.
We're doing 4 in June and I wish we had 5 now. Our plan the first day is ride everything we have to do or want to in DL minus Galaxy's Edge. We're going to use Touringplans to help create a plan combined with Disneyland Daily's great DL plan on using
Genie+. Our 2nd day is California Adventure. We love that park but find that one day is usually enough. We use TP and DLD again for that too. Our 3rd day will be at DL and the plan is to start at Galaxy's Edge. The afternoon will be going to the items we didn't accomplish on day 1. Day 4 is just our lazy day. Take it easy, ride the train, ride the Main Street vehicles, wife and I are going to Trader Sam's. Our teens can go on their own and have a good time. Wife and I wanted a day where we could just relax and enjoy Disneyland for what it is.