To answer your question, there is no set time between warning and locking.

The reason why there may be considerable time between a warning and locking has to do with the fact that Mods and Coords seek advice from one another. I may be a little uncertain what to do with a thread, and I will post a message in the coordinators forum asking my colleagues what they think. if I decide to do this, it may take several hours to get enough feedback to factor their advice into my decission.

There is great deal I could tell you about the process, but most of it is boring to anyone not involved with the administration of this place. In the end , it is all judgement calls, and those of us who make the calls do our best to be reasonable and fair.

(What was it lmckensie said about a Moderator's job being "herding cats"?)