In D&D Next, Inspiration can be granted to a player for good roleplay and playing your background's bond, personality, ideal or flaw. Because inspiration is not cumulative so you have it or not, it seems like it should be frequently awarded assuming the players roleplay well.
Because inspiration allows you to gain advantage (or cancel an enemy's advantage), I'm wondering if awarding it too much could change how I plan my encounters.
Are there any guidelines on the frequency of awarding inspiration? If they get inspiration only once per 2 sessions, would it change the balance of the game? If I give them inspiration after every fight (like a Lawful Good character sparing an enemy every fights because of its background), would it be too much?