One of the beauties of being a Sorcerer is that you can select any spell from a given spell level depending on the circumstances and current needs, therefore maximising your spell usage. Before getting Project Image, I roughly need about 1-4 rests per major quest. When I obtain Project Image, I can afford to rest once every 2 major quests.
In some cases... it also depends on what the quest is, and what spells I have. For example,
ONE Skeleton Warrior can clean house against the melee Gnomes and Sahuagin in the Planar Sphere, and absorb most of the spells that their spellcasters use. My Sorcerer can then use the Sling of Everand to KO all the Golems in the Golem Room and Engine Core Room.
That is
ONE spell.
Is it cheese? No, it is not. It is simply frugal and smart usage of spells.
The better but cheesy option is to cast ONE Project Image and get 6 Skeleton Warriors. Proceed to use them one by one. 