Was on a webinar and the presenter mentioned that modelers should "slice" in certain contexts to reduce MIP solve time. The context was in sending a Minimum Cost Network Flow Problem. I believe he was referring to pre-evaluating Binary variables in some way. Possibly stacking them in a matrix? The effect was to reduce the solve time. Is anyone aware of this technique? Can't find a reference.
EDIT: some more color. When doing a worker scheduling problem, it's common sense to use the workers availability for a given time period(1 available or 0 unavailable, but not a decision variable) to reduce the number of decision variable created. I believe this was the reference. Simply ensuring you don't create decision variables that we know the value of prior to solving.
I gave that talk. The term "slice" for iterating over a subset of indicies based on an outer set of indicies was originally invented by Robert Fourer for AMPL (AFAIK). I believe this term appears in the AMPL documentation, and I'll swear on a stack of Bibles that I've heard it used this way both by Bob himself and by senior Gurobi people. At any rate, the documentation here does a good job of describing what I'm talking about, and you can see different forms of slicing in action in the netflow example here or here. Sorry if I confused you with this term.