There is a rule against successive motions for summary judgment.  The usual understanding is that you get one shot, and if you take it too early, or upon insufficient evidence, then too bad.  However, in Alaimo v Mongelli    2012 NY Slip Op 02071    Decided on March 20, 2012  Appellate Division, Second Department  we see a different result.
 

"Contrary to the plaintiffs’ contention, that branch of the motion of the defendants Michael F. Mongelli and Michael F. Mongelli, P.C. (hereinafter together the Mongelli defendants) which was for summary judgment dismissing the first cause of action in the amended complaint insofar as asserted against them "did not violate the general proscription against successive summary judgment motions because it was based on deposition testimony which was not elicited until after the date of the prior order denying the earlier motion for summary judgment" (Auffermann v Distl, 56 AD3d 502, 502; see Staib v City of New York, 289 AD2d 560). "

"Here, the Mongelli defendants established their prima facie entitlement to judgment as a matter of law dismissing the amended complaint alleging legal malpractice insofar as asserted against them by demonstrating that the plaintiffs would be unable to prove, inter alia, the element of causation (see Humbert v Allen, 89 AD3d at 806-807; Marino v Lipsitz, Green, Fahringer, Roll, Salibury & Cambria, LLP, 87 AD3d 566; Pistilli Constr. & Dev. Corp. v Epstein, Rayhill & Frankini, 84 AD3d 913; Markowitz v Kurzman Eisenberg Corbin Lever & Goodman, LLP, 82 AD3d 719). In opposition, the plaintiffs failed to raise a triable issue of fact (see generally Zuckerman v City of New York, 49 NY2d 557, 562). "