cmad1977
Hero
Groups tend to focus on things they find particularly powerful. In my first game we had a half-elf red dragon sorceress. Once she got to 5th level, fireball began its long and glorious career. Starting about 9th level, at least 1 fireball appeared every encounter; often it was two. She tried to diversify, but found that upcasting fireball was generally better than most other choices (this was pre-XGtE). The only time I got a break from fireball was when they went into a volcano to face off against fire giants and a red dragon, and even then it made an occasional appearance (she could ignore Resistance, but not Immunity). This continued until level 18, when the campaign came to a close. As a DM you just kind of get used to it, because the focus may change to something else over time. My group is currently focused on Suggestion, Spirit Guardians, and Sickening Radiance.
Twinned scorching Ray and Haste were my “fireballs” in this scenario.