We have done quite a few of these now. Mainly for about a week.
We love the freedom of going at our own pace, and to also divert. You need to do your own research as to what to see or do along the route as their notes basically cover navigation rather than sightseeing.
You can sleep in and leave later, or get up earlier.
We check out the weather forecast and work around that. IE might dodge the rain. Or if really hot we might cycle mainly in the morning.
Sometimes we will deviate off the route to take in an extra site.
We often add in extra days too. Sometimes to just to sightsee more at a particularly interesting region.
With the Coast2Coast across England with did it in 5 nights rather than 3 so we could enjoy it more.
We have also organised some ourself without bag transfer. IE 9 day circuit in the Alsace. We just in advance arranged bicycle hire, but planned our own route and booked our own accommodation. This option means no support though and so you need to know how to fix things. IE one chain broke. I had my own bike tools with us and so just fixed it in a few minutes. Bike shop ended up refunding all the bike hire cost and so that broken chain actually worked out well for us.
Apart from the freedom I find the experience more authentic as you spend most of your time in non tourist spots, and often interact with locals along the way. Many of the lunch and cake shops, cafes etc can be more the normal local ones than ones for tourists.