I've done this in a number of cases -- sometimes easier to have a long-term hotel room than an apartment.
The IHG Ts and Cs don't appear to have any limitation on the length of a "stay" but I would check and get it in writing .. I know at one point, SPG had a limitation; a friend was advised to check out for a weekend when away and check back in (plus that saves the company money) and that got her to "ambassador" status with a personal concierge, etc.