The whole duration thing is overrated IMHO....how often do we really see 1"/hr+ snows protracted over the span of 24 hours, anyway? Occlusion will usually limit it.
The real key is to have H85 through H5 close off about over the cape....its about track and timing of developmental lifecycle of mid level lows. Get that right, and I'll show you 2'+ in 12 hours. Just speaking in a theoretical sense...NOT a forecast.
What a blocky pattern does is not only buy you that extra 6", but it makes the amplification and/or phasing needed to get those type of systems more likely...not to mentioned preventing too much amplification.
The stalling notion may mean the difference between 24" and 30", but its not as a big of a deal as folks think, unless you get off on an extra 12 hours of currier and ives like Kev.