Two Types of Fillibusters

Ezra Klein says:

As we've discussed before, the reason holds and filibusters and cloture calls and all the rest of it is so effective is because the Senate operates amidst a scarcity of time: There's a lot the majority wants to do and not enough time to do it.

I think it's important to distinguish two different things here.  One is, let's call it the capital-F Fillibuster, which is effective because Senate rules require 60 votes for cloture.  If you have 41 votes against cloture, you win (barring further bargaining, or use of reconciliation, etc.). 

The other kind, the lower-case filibuster, would include any kind of general stalling and foot-dragging, generally by minorities smaller than 41.  This can include anything from holds, to forcing cloture votes (which can kill hours of floor time even if they are uncontested), to using post-cloture debate time, to forcing bills to be read, and on and on.  Those filibusters are effective because floor time is scarce, but can be defeated if the majority is willing to spend that valuable resource.

(In practice, the two often compliment each other, or blend into each other -- it's sometimes hard to know whether the minority actually has the votes to block cloture without taking the vote, so it's sometimes hard to know which kind of filibuster is going on, and for low priority things it often doesn't really matter, because lower-case filibusters may be sufficient to kill low priority items).