The only reason I think a person use a drink is if you see your heavy hitting friends arn't online. I tend to use the elixir if I run into a weak EG.

But I am one of the fortunate people who has a pretty high SED (even without the slayers). So halving the an SEG would only insure the lower level friends have an even shorter time to poke the bear.

When I'm not playing on my phone, I try to share SEGs to lower hitting friends first and then work my way up to the heavy hitters. For a lot of people, it's a race to 300 SEGs, which will be a long, arduous process. To ensure that we all get there, I would say keep the drinks to a minimum unless you plan to solo the SEG. Can't blame you if you do, but short of soloing it, save more for those at the bottom.