First, selling 100 ES straddles is too much risk to undertake in my opinion but I know you were just asking a hypotehtical.
Delta hedging is something maybe market makers do with their almost no transaction costs and constant hedging I assume. For anyone else, delta hedging is a way to make your broker rich in churning your account and serves no useful purpose. When I sell straddles ATM or directional, I have a market price level where if it hits either or the straddle gets to a certain value I bail.
If the straddle decays nicely but I still want to do it, I will buy the wings only if I like the Iron Fly that would result.
Honestly I rarely do this strategy because i want the right conditions to make me comfortable, everybody is different. I prefer when ES is setting up to range and vols have good chance to pull in (it is more a vol trade than a theta play). Now I perfer trading volatility and ignoring market direction all together because it makes it easier to monitor.