Googles pagerank sometimes drops and sometimes not....

Surferfriendly websites rated differentby google

[baron13]

Many website owner use a surfer freindly navigation. For example: they place all important link on the left site and you can see this navigation at the main dimain and at all subsites too. NORMALLY the pagerank should not drop at these pages because they ar interlinked very well. But sometimes google drops that pagerank and sometimes not! Why? There is no reason for that!

And how lon will it take for subpages to get the pagerank from the homesite?

[2_much]

It depends on how they're interlinked and if there are links pointing to the inner pages. If the inner pages are only receiving links from each other, typically the PR will drop by 1 level of PR. If they're receiving links from other pages, this might boost the PR of the inner pages. Remember PR works on a PAGE basis, not on a SITE basis.
As to when the links register - this depends upon when they were spidered.