What adjustments do good bidders make for seven card fits?
Good bidders prefer to rebid in NT with any balanced or semi-balanced (ie no singleton) hand when a 4-card raise is unavailable. This quickly refines both range and distribution of the opener's hand, enabling more precise bidding by both partners. Only weak players rush to either show 3-card support or to rebid 5-card suits.

One exception to this rule is in a competitive auction where 3-card support is combined with shortness in the opposition's suit. Having a doubleton or singleton in opponent's suit as well as 3-card support is information too valuable to either hide or delay showing in a competitive auction. Knowing that the ruffing value is well placed, and with opponent's fit known to increase the likelihood that partner has a 5-card suit, the risk of a Moysian is reduced.

Further, established partnerships generally play New Minor Forcing (or some other check-back convention) over opener's NT rebids to facilitate finding both 4-4 and 5-3 fits in Responder's suit(s).