I like the idea, but find the color bands a bit distracting since they're obviuusly incorrect - actual travel times are going to be shorter to navigation hubs and longer the further out in the network you get. It'd be more complicated to implement, of course!
This is why for this kind of map the geography is usually left as-is in one of the usual common projections, with a colour scale marking the time-distance, rather than distorting the geography.
Agreed. These might be nice to have on the wall, but there are a lot of projects that have produced accurate maps over the years. A Google for "travel time map" brings up loads, such as https://app.traveltime.com/ which lets you make your own.
