User blog comment:B214/Question and Answers 6/@comment-2607:FB90:60EC:D657:817F:69A8:773B:7587-20190427204813/@comment-181.115.110.208-20190428010412

He wasn't, he fire infinite blaster to blow up the field, an hour of rest isn't really enough to recover the stamina he lost. Back in later volumes when Issei used longinus smasher he can only do it once a month or so. I know that he's stronger know but still  one hour or a couple of rest wont help him that much.