I started prepping for Brexit around 18 months ago and gradually built up ~ 6 weeks worth of stock which I have maintained ever since.
I didn't specifically prep for the covid panic buying in March (by the time anyone saw that coming it was far too late) but I was extremely glad I had enough in that I could completely avoid the shops until things calmed down.
I wasn't one of those people 'adding just a few extra items and shopping more often', I was able to stay well out of the way, leaving more on the shelves for those who needed it. There were lots of empty shelves near me, I went to my local big tesco to pick up a prescription and it was like locusts had been through. And there was a very noticeable tense atmosphere among shoppers. I live somewhere where things can kick off very easily. At the worst point I reckon we were 1-2 days away from food riots here.
YMMV, I'm sure you live in a lovely jolly village where everyone pulls together and there's never any unpleasantness and never any shortages. Bully for you.
I was also extremely glad I had enough in so I could put an emergency box together for DM when her delivery slot got cancelled with no notice and there were no more available for the forseeable future. Never mind covid, a trip round a supermarket would likely finish her off! Thank goodness she was on the shielding list and got priority slots but that took a few weeks to sort out and in the meantime she was stuck.
And there are a huge number of people who rely on deliveries because they cannot manage going to the shops but who weren't on the shielding list - many of them were reduced to relying on the kindness of non-DBS-checked strangers. This is not a marvellous heartwarming thing, it's shit and it's dangerous. People who hoard delivery slots they don't need (you know who you are) deserve a special place in hell. That's probably a topic for another thread though.
I was glad to also be able to help out next door when they'd been unable to find basic necessities in the shops because the shelves had been stripped and there weren't any delivery slots. Four children and no bog roll is not a recipe for fun.
So I ran my stock down in March and April and built it back up again over the summer when stock was relatively plentiful. I can now stay out of the way of people suddenly realising they could be confined to their homes for up to 14 days, and people suddenly realising brexit has not gone away and we face a cliff edge in 12 1/2 weeks which is likely to cause major supply issues.
I don't feel smug, I feel extremely grateful for the advice of @bellinisurge and other regulars on the preppers board. Thank you from a long-time lurker 
I think a lot of the sneering responses on this thread are just whistling in the dark.