So I managed to get my rogue to level 90 today, so have the first set of results on the delayed leveling route. This involves staying in the earlier zones a few bars longer than you otherwise would before skipping to the next zone. So I stayed in Jade Forest until about 6 bars into 86, stayed in Valley of the Four Winds / Krasarang until just a few bars from 88, stayed in Kun Lai until half way to 89, and stayed in Townlong until 7 bars into 89.
For my previous 6 toons, not counting the character I started on launch day (always slower), my leveling times have ranged from 21 hours to 25 hours played time from 85 to 90.
For this character with the slightly delayed leveling approach, his total played time to 90 was 20 hours. Imagine my surprise to find that doing it the "long way" actually resulted in a faster leveling time.
I'm now somewhat curious as to what the speed would be to totally play out each of the early zones.