It's so personal, even though the sums are technically objective facts.
I chose to fix for 5 last year simply because I found coming up to the end of my old fix so stressful (it was in September and things were just starting to get crazy - I was lucky to secure a rare before they totally rocketed but still pay much more than I did before.)
I did wonder about fixing for 2, in case things came down...
But - ultimately, I thought about two situations, in order to decide.
"How bad will I feel if, in 2 years' time, rates are available that are lower than the rates I'm still paying on my 5Y fix with 3 years to go"
Vs
"how bad will I feel if, in 2 years' time, things are still turbulent and I'm going through this hell again, checking the news about rates every morning and panicking about what deals I might be able to secure for my next fix?"
And tried to imagine really hard which of these two crap situations I'd find the least crap.
I decided that personally, I'd find the first one less crap. I'd be pretty used to whatever my monthly payment was by then and would have just come to accept it as part of life. Whereas the stress of scenario 2 just made me scream NO.
That's because I'm not a risk taker, and am quite anxious. Some people are much more open to a level of risk that I prefer to avoid and get less anxious than me, so would make a different choice.
Game it out in your mind, know thyself and pick whatever will bring you most peace.