Another factor is that English dances usually specify the tune that goes with them. Contra dances very rarely do. So if a dance series has a house band that plays most of the time, as some of the Bay Area English dances do, then a repeated English dance may be the same figures done to the same tune played by the same musicians. For a contra, even if the same band played the same set of tunes, it's typical to change tunes partway through the dance, anyway, so it's hard to achieve the same degree of repetition.

Of course, repetition isn't always looked down upon. I've heard that the weekly dance in Nelson, NH always has Chorus Jig on the program, and other dances that repeat week to week. Some contra dancers do appreciate recognizing dances - ah, Poetry in Motion, I know how that one goes.

As Mac says, the type of repetition that contra dancers really notice is within an evening - when four dances in a row have heys, or half of the dances have Petronella turns, and all start to feel the same... and that's a type of repetition that's less likely to appear in ECD, where dances that have similar figures could easily be done to different tempos or meters.

Personally, I keep track of all the dances that I've actually called, because I don't want to call the same dances all the time; most of the time it's slightly different from what I programmed originally. I add notes to myself if something didn't go well. I can't remember if I've been asked by organizers for my program, but it may have happened once or twice.

Hope this helps!

Yoyo Zhou