I did a six day for London next March, mirroring the time I just got back from 6 days in London, and:
Day 1: Close to what I did, we did something different for dinner, a lot closer. (it's funny because Rick connects the Tower of London with Westminster via boat, while I thought walking to St. Pauls would be better, and the AI agrees with me).
Day 2: I wonder about doing the Abbey the morning after you did the St. Paul's the previous afternoon. This is my quibble, as I like to space out similar major sites... art museums, palaces, and big ass churches.
Day 3-6: We only intersect on two more sites, three if you count Kew Garden, which we canceled because everything interesting to my wife was closed.
It's not the worst place to start, and might be clever for restaurants, though most of them are not really located close to the sights you're closing with. Great if you're cabbing all over, not necessarily good if you're on the toe heel express, and want something easier.
It asked if it could change anything for me, and I said "Most history and art" (meant to type "more"), and it's head exploded. Simplified to "Remove Changing of the Guard" which it processed for a bit, and then ignored. I put in "remove buckingham palace" which condensed it to five days, from six. Asked it to make it more walkable, and it did, kind of. Day 2 changed the walk after the Abbey, but it's not necessarily more walkable.
Needs a bit more work, but interesting to aggregate and assemble the top sites on wherever. Thanks for the share.