Not really, no. I chuck a few dummies about for the older dog very occasionally, but he only really comes alive around birds. And I do a couple of working tests just to remind myself as much as him about what we're supposed to be doing! But he's pretty much as trained as he'll ever be. Otherwise he does agility in summer as a 'filler'. The other one is only just a year, so has regular training (daily) - he won't be out this season I don't think.
I find it very useful actually. Aside from him totally loving it, it gets him fit (and me too), and gets him used to the birds before the first shoot day. It hasn't ruined him yet. He does range quite far while dogging in and runs lines along the hedges, but he doesn't chase birds once they're up and he's responsive to the whistle. I suppose it could ruin a dog if it was inclined to bog off a lot anyway. Pip just isn't, so I'm really lucky. He's done 2 seasons dogging in and beating/picking up and he's worked fine beating after the dogging in. So I do think he knows the difference. Suppose they're 2 very different scenarios. Hopefully he'll be just as good this season. I've done little bits of him hunting a pattern and he remembers that fine.