Originally Posted by JMich

Scaring the EGs into fleeing means less encounters in the long run.

I disagree. The main constraint(resource-wise) on the number of SEG's you will seduce is focus. If you attack an EG, then that means the total sum of SEG's you can attack decreases by one.
Stamina is abundant in the EG-event, and so is pero. Using it does not constrain the total amount of SEG's you can attack during the event.
Therefore it makes more sense to use it to spawn new SEG's.

The only time I see attacking EG's during phase 2 as valid is if focus is abundant, which would only happen if your pero/sta is constrained, or if you don't have enough active friends.

As for halving HP:
I always look through my friend list to see who is online and to calculate how much SED is available when I first spawn a SEG. If it falls well short then I halve it, otherwise I might be forced to try and land lots of extra attacks(waste focus) or to see it flee.
Only someone with really high SED would say that it is a waste to use drinks. For low level players it can be a struggle and worry to get the SEG's you spawn to get seduced.