He probably has all troll farm-able girls already. I think most games with gacha like mechanics only give slightly higher priority for event girls, to incentivize people to spin more to get them. Thou at least in games like FKG you at least know that there will be a reissue of the event with reissue gacha to let you try more times later. HH has rare special events that let you get all older event girls, which is a worse way of doing that for us players, cause with more event girls in the pool its harder to get who you want.