We did this banner in a group of eleven agents. It took us 7.5 hours, but we had some delays due to sim card/tethering problems and one agent being temporarily speed locked due to an ill-behaving gps.
The missions string together most portals along the way in an efficient and unique visit friendly fashion and leads around a large number of beautiful places and neighborhoods. Occasionally in the last third/quarter of the banner, the portals to visit are further away from each other, but not to a degree where it would make sense to pocket your scanner. A few single missions can be completed walking just a few steps.
Most sections are electric wheel chair friendly, there's always a lowered curb nearby to cross the streets; only in the 5th and 36th missions there are steps, but it is easy and not far to go around. For hand operated wheelchairs the banner is nearly impossible to do in a reasonable amount of time, there is a lot of cobblestone, partly very old and bumpy, some of the narrower pedestrian curbs can be flooded with unpredictable tourist groups and locals :(
at the beginning the portals are quite far apart, but it gets better about 25% into the mosaic. occasionally some going back and forth (a little bit too much for my taste). but otherwise a nice way to see mulhouse.