Epcot: I don't see how you can do less than 2.
Not sure I agree with this, but it depends on what the OP wants to do each day. If a person is content to do TT and Soarin' only one time each, they could do one RD and hit Soarin' at 9:00, and then TT later in the day. After Soarin', one can tour the rest of Future World rather easily between 9:30 and mid-afternoon hitting every other attraction that builds lines and use the rest of the day to visit pavilions that do not involve lines. Odds are that a second day will be needed to mop up the things that were skipped on the first day, particularly in World Showcase. But that wouldn't involve arriving at RD. On that second, non-RD day, you would get a FP for either of the headliners, but would have to concede that the other headliner would have to get skipped. This is admittedly not a "do everything every day" commando touring style, but it is unclear to me if that is what the OP is asking for. So consider:
Day 1:
Soarin' at RD
Sum of all Thrills at 9:30
Mission Space at 10:00
Living Seas, Ellen's Energy, Journey Into Imagination, Living With the Land and lunch all between 10:30-1:30.
Innoventions, Spaceship Earth (using FP) and Test Track (using FP) between 1:30-3:30.
Remainder of the day at World Showcase.
Day 2.
Arrive at your leisure and hit anything in FW that you might have missed, maybe using your FPs in the morning.
Go to WS when it opens and go to Maelstrom.
Tour the rest of WS hitting what you might have missed on Day 1.
Return to FW in the mid to late afternoon to use your headliner FP if you didn't use it earlier in the day.
This two day Epcot plan gets you to everything in the park in a fairly leisurely fashion with only one RD. But it doesn't attempt to "do everything" on either day. I'm fairly certain that this is the style and pacing that Disney is pushing us toward with FP+ and trying to fight against the tide may not be worth the struggle.