In my experience routine trumps almost everything. And considering language learning, religion, accents, etc, routine probably trumps everything, period.

I've seen enough parents carting bored kids through supermarkets, while walking sullenly and silently, to know that some people aren't even trying.

The vast majority of kids will be just fine if you take them grocery shopping. Yes, exceptions exist. But "just take the kids shopping" is good advice for almost everyone.