I've wondered about that. I mean, you're essentially retired, you're a cancer survivor several times over (maybe) and you live in the place where you recreate. Did SM only bike on Sunday mornings? Did she prefer to bike on Sunday mornings? Was it merely her routine to bike on Sunday mornings? Was it set in stone that she biked on Sunday mornings? Would her family and friends have expected her to bike on that Sunday morning?
I'm a cyclist and during non-COVID times work full-time. So I have to bike on weekend mornings, and if my family needed to get in touch with me that's where they'd start, rain, shine, snow or cold. But if I were a Scapa of leisure and could bike whenever I wanted to then I'd pick the more pleasant times -- just as I'd pick warmer, sunny, less windy days to ski if I lived in ski paradise rather than forcing my tired, aching body and grumpy kids out into a howling blizzard because we're only here for a week every 4 years. So unless I were training for an event my routine would be a little less, well, routine.
My point is, I guess, that we seem to know very little about SM's routines, patterns, broader way of life in order to try to make sense of this aberrant moment, this hard fracture of routine and normalcy, when she disappeared. My sense is that we know so little because it doesn't matter that we know, because no one is really looking for a missing person. They're looking for evidence of a known/strongly suspected crime.