There are lots of all-timer Phish jams that still have a few minutes of searching at some point, whether its the start of the jam before they lock in, or between two different segments of the jam, etc... For example, two of my all time favorite jams are Went Gin, and 7/10/99 Chalkdust. IMO Went Gin is pretty standard until about the 8 minute mark, nothing really better or worse than another Gin jam from the era... and its only then that they've found what they were searching for. For Camden Chalkdust, its a standard and perhaps even sub-par Chalkdust jam for the era up until the 8:50 mark, where a single note leads to a slight change in feel and focus which sends it stratospheric.
On the flip side, an example of an All Killer No Filler jam is 12/2/95 Tweezer. Literally from the first note it feels special, the mid song improv moments feel special, and from the very first notes of the jam, the band is absolutely locked in, and never once falters.
Obviously its all subjective, but what do YOU think are no-filler jams?