I can think of logic chains that point either way, but I don't have the knowledge or evidence to favor either. (While my reading on the topic may be more technical than that of most (non-medical) people, I have only have a layman's knowledge of the transmissibility of corona viruses and even the experts haven't had much time to learn about this particular one.)
Remember too, that one needs to factor in not only the direct exposure in the store (which might be proportional to time in the store), but indirect exposures due to pickup on clothing, shoes, the interior of one's car, etc. (Medical people often remove their outer clothing at their front doors and head directly to the shower to minimize the chance of bringing the virus in their homes.) The indirect exposures could be proportional to the number of visits.
I personally try to make my visits as infrequent as possible--it is less stressful to deal with the post-trip clean up once rather than 10 times. I quarantine or disinfect everything that comes into my house--according to one study, the virus can live up to 3 hrs in air, 4 hrs on copper*, 24hrs on cardboard, and 2-3 days on plastic and stainless steel.
https://www.technologyreview.com/202...nd-on-packages https://www.medrxiv.org/content/10.1...217v1.full.pdf
* I have seen the suggestion that door handles, handrails, and counters in public places should be made of copper because of its germicidal properties.
Doug