Based on my own experience as well as that of some others (most recently Jason*), putting a typeface design in development away "in the drawer" for an extended period allows one to come back to it and generally immediately see what needs improvement, both on a macro level (eg lower contrast) and a micro level (eg the tail of the "g"); but presumably this tactic has drawbacks as well (for one thing it precludes the case of working with a commission deadline). This is not something intuitive, and typically it happens without intent; but if it works maybe we should do it actively. Also, this does not mean the overall rate of development need slow to a crawl: one can have multiple designs in the pipeline simultaneously** and maintain the same rate of release over time. On the other hand, many people can't properly develop more than one thing at a time.
* See first post of 3/6/09 here:
http://typophile.com/node/41105
** Which actually has its own benefits in terms of cross-pollination.
In some cases it has taken a designer over 10 years to finish the font (and presumably in most of those cases there were long periods of total inactivity) with stellar results (Beorcana comes to mind). In other cases a designer has returned to a design years after its release and made -or at least desired to make- a markedly improved version (Slimbach's Garamonds come to mind).
I'd be interested to learn who has used this tactic, what insights they've gleaned about it, and what they feel is an optimal hibernation period.
hhp