You may have a job that lets you get some writing done during down spells: perhaps your main role is to wait for phone calls, for instance, or to answer emails quickly as they come in ... but you don't have other work you need to get on with.
This can be a great opportunity to squeeze in some writing, especially if the rest of your day is very busy.
But when you can only write for a very short period of time (think 2 - 5 minutes), then you may well find you're just getting into it, only to be interrupted.
If you're at home with small children, or if your kids aren't in school due to Covid, then it can be incredibly tough to fit in any writing time at all. Maybe every time you open your laptop, someone immediately needs your attention.
I still think it's worth writing. Even if you only manage a few minutes at a time, those words will still add up.
Here are a couple of things you can do:
#1: Continue to seize opportunities to write, even if they're not ideal. Ten minutes is fine. (Katharine Grubb has a whole book on this, Write a Novel in Ten Minutes a Day, detailing how she writes in 10 minute bursts around homeschooling her five children.) Even if you can only manage 2 - 5 minutes, that's better than nothing.
#2: Where possible, try to work in some longer, uninterrupted writing sessions – perhaps once or twice a week. These don't have to be very long. 30 - 45 minutes would be great, but even 15-20 minutes could work.
If frequent interruptions are making it really difficult to write, but you still want to use the time productively, then you could look for non-writing activities to do instead. Reading might well work, or you could also do pre-writing activities like coming up with ideas, jotting down an outline for a blog post, working out what should happen in the next scene of your novel-in-progress, and so on.
Writing around interruptions can be frustrating... but it's definitely better than not writing at all.