Alegrias1
I went and had a look at the study on which this is based. I tend not to agree with the cries of rubbish as the headlines are usually based on good solid research which the press decide to interpret as they see fit.
What I learnt:
Those who went shopping once a week have the highest chance of catching Covid.
Those who went shopping more than once a week have a much reduced chance of catching Covid compared to those who go once a week.
So probably, there are other complicating factors at play and the people who go shopping exactly once a week are exposing themselves to other risk factors as well.
As you were.
Maybe the increased risk for shopping once a week, as opposed to more than once, is that those who go once a week are more likely to spend longer inside the building. Also, you will probably be in contact with the same people for a longer time, especially with a one-way system that means everyone's taking the same route. So although if you go more often you will be in the same building at the same time as more people, it's not so likely you'll be in contact with an infected person for long enough to get a sufficient viral load.