Could swim, would swim, or want to swim?
I could swim a 100 (if absolutely necessary), only want to swim 50 or less, and would do everything possible to get out of swimming the 100.
I did a 200 fly when I was a kid one time... that's it, never again.
I seem to only have one speed with Butterfly so anything past a 100 is a no go for me. This past weekend I did the 100 and 50 fly at the UCLA SCM meet. My 50 fly was the same as my split time on the first 50 of my 100. The second 50... not quite as good, but I'm working on it!
A few years ago I did the 1000 FR as a fly swim at the CO state SCY championship meet. My goal was to break 20 min and I hit about 18.
The next year Erica Leetmae swim the 1650 as a fly event. Her fly time was just slightly slower than my freestyle 1650 at the same meet.
I put 50, but it wouldn't be much of a race. I just started swimming fly a few months ago, and have just gotten to the point where I can swim it decently with fins. Just barely at the point where I actually do the last 100 of our 400 Reverse IM warmup, instead of making it a 300.
The most I've tried so far without fins is a 50, and the last 10 or 15 yards were pretty ugly.
I have done a legal 200 fly in practice. But I think I'd be faster with breaststroke. I would never race a 200 fly though. I haven't raced a 100 fly in four years though I regularly race 50s.
There is a chance that I'd take advantage of the Masters rule that allows breaststroke kick....