OK I have read that even if you have had an endometrial ablation you are given progesterone in case any of the endometrium is left. I haven't read enough about it to know how many women bleed afterwards still, but maybe they cannot tell for certain if there is any left.
From my ordinary knowledge, I would have though that if there was any endometrium left - then even if it didn't cause bleeding though your normal cycle, you would be stimulating it through HRT, and therefore it need to be shed - through taking progesterone cyclically as you have been advised.
I would imagine if there is no endometrium left ie the op was completely successful, then you would not get a bleed - but you will have been prescribed it just to make sure.
As I said before any fragments remains elsewhere in your body if you had endometriosis, then you would have to have progesterone and I'm not sure even if HRT is given in these cases? Maybe continuously to stop these areas building up? Probably doesn;t apply to you loveydovey.
There is an endometrial ablation discussion forum but you might not want to look at that because it will have all the post op horror stories!
I hope that helps?
Hurdity