The workplace can seem a strange place to write "flash fiction", as far as some people are concerned. I wonder how many people think to themselves, "I think, during my lunch, I'll write some flash-fiction"?

Yes, it can be done while having your lunch break. The other week, I was lucky enough to attend a half-hour flash-fiction bitesize course, which I thoroughly enjoyed, and it taught me things about "flash-fiction" that I hadn't even known.

So, if you want to give it go, then do so.
It's good for mental health, which gets mentioned a lot in this day and age, and is even better when you can do it as a group, and have the friendship and community spirit that group-writers enjoy