I think it depends a lot on context and your co healer. If I use EOS HoTs and my co healer crushes them by topping everyone off, you can bet I'm not going to bother anymore, might even pull Selene out.
If my co healer is topping tanks after busters... I'll save my excog. etc.. etc.. Hell, sometimes you're just waiting for misama II to fall off so you can weave your indom (becaue you know there's no damage output on it's way) and the other healer tops everyone off.... Fine I'll just use my aetherstack to dps.

I find that pugs are often a bit of a tug of war between healers. We try to come to a silent agreement on who heals what/how whilest getting as much dps out as possible.