Yep, quite often, I use a rack and the topeak trunk bag with the fold out panniers, can fit a fair amount in, say a full supermarket carrier bag each side. Tend not to cycle back more than a mile (I have full size Tesco, Sainsburys, Asda,
Morrisons, all within a mile or so...and a baby Waitrose)
The Abus D lock goes in the trunk part, no concerns leaving bike outside any of the local supermarkets with one of those
Very very rarely use a rucksack, don't like carrying stuff on my back
Bigger shops = car, but even then I'm shopping for one, just bulkier/heavier things like cans of pop, loo paper, washing stuff etc, that's not common in the summer