This.It is hypothesized that there are two species of BTA, one that grows large, lives as an individual and tends to reproduce sexually instead of splitting and one that lives in large colonies of clones that don't grow large as individuals, but instead split at a smaller size and grow large as a colony.
If your anemone is large and has never split and is not the result of a split, I would be hesitant to cut it as it may be the form that doesn't normally reproduce asexually.
I have seen way too many large bta split to believe that only the small ones split.