@Mzokk I also only use a track as an underlying reference while driving a route. Probably I didn't read your aswer correctly for which I apologize.
When you choose the direct routing profile before converting a track in BC to a route, you have the possibility to enter how many shaping points you want to use as you mentioned in your reply (probably missed that picture as I only saw the track to route convertion ones). I normally use about 45 to 50 for a 300 km track. Once recalculated with faster time, I drag the route to the track where it differs, then I recalculate the route with shortest distance and do the same (I have 2 motorbiking profiles in BC with the same avoidances one with faster time and one with shortest distance). If I see that there are too many shaping points on a straight road, I delete them as they have no use. Recalculation mode on my zumo stays on automatic. Never had a problem when diverting from the route as a new route to the next shaping point is calculated. You can even use the skip button without any problems. I have been using this method since 2016 and every zumo can be set to automatic recalculation without any problems.
Optimizing a route in MRA as above is a real hassle as you first have to save the route as a track before you can import it again in your track logs and use it as an underlay before you start using the toolkit to first set the number of shaping points to '50' i.s.o 99 and start optimizing your route the same as above or change mapset. I've been asking for moths for a 1-click track creation from the route in order to avoid all this hassle. Perhaps it will come some sunny day?