I booked the gym for four hours on Thursday and Friday.
I reserved the music studio for four hours on Thursday and another four hours on Friday.
ーI booked the gym for four hours on Thursday and Friday.
「木曜と金曜に4時間ジムを予約した」
to book ... for four hours on Thursday and Friday で「木曜と金曜に4時間…を予約する」
ーI reserved the music studio for four hours on Thursday and another four hours on Friday.
「木曜に4時間、金曜に4時間、音楽スタジオを予約した」
to reserve ... for four hours on Thursday and another four hours on Friday で「木曜に4時間、金曜に4時間…を予約する」
ご参考まで!