The Sherman jumbos were issued pro-rata in platoons to US Sherman battalions. They were not that popular as they had less operational readiness and the weight stressed the Sherman's components too much. (lower than the superb 90-95% that US tank battalions generally had). The Sherman was not designed to carry that kind of weight.
Well the Jumbo could bounce Tiger shots so.. They were also in high demand, some Tank Divisions even attempted to make their own when they failed to procure any. Those were called Expedient Jumbos, and made from extra armour, or armour from damaged Shermans and Panzers.