Based on my extensive experience locally, and more limited experience elsewhere, in the wilderness there are a lot of waterways which have more than enough to packraft, but not enough water to be consistently free of wood.  In a place like Alaska, which generally lacks human-built trails, the calculus is different.  But in the lower 48 the efficiency of these streams and rivers is often questionable at best, at least in terms of time from A to B.  Over a long trip floating is often more fun, and with proper terrain reading and efficient technique what seems like slow floating with frequent portaging can still be at least as fast as hiking the parallel trail.

The only way to cultivate this is of course to get out and practice, which is both fun and frustrating.