This subject is kind of subjective and kind of not. SOme reasons are technical, and some are preferential. I can only give my advice as to how I like to work and it may or may not apply to all. The technical reasons are more cut and dry.
There are times when I am editing on site and there simply is not time to log and capture. I need the footage in the system and I need it yesterday. It usually means I spend more time dividing up the clip later into subclips and renaming, but I do it as I need it, not before.
If I have the time at the studio, I choose to log and capture as I can look at the list of clips with their log notes and know exactly what I have. Also, if the other editor in the office and I are tag teaming a project (which happens from time to time) he can then sit down to my project and know pretty much what each shot is before he even has to look at it, while I can sit down to a project that he has started and do the same thing. This is helpful if he didn’t watch any of the footage while it was digitizing. I feel as if when i log and capture I know everything I have because I am watching almost every frame shot. If i digitize the whole tape in one pass, there’s more of a chance I’ll miss something if the phone rings, an email comes, the door bell rings, etc. If I do remember a shot in a half hour clip that I have digitized at once, then it takes me that much longer to find it by sorting through a 30 minute clip. If it is logged and captured correctly and I can simply do a find for what I want or quickly scan the browser/log notes for the clip I have described.
NLE systems (in my experience) seem to get less bogged down if there are shorter clips to work from. When you start getting clips that are too long, the system really starts to drag, especially on slower firewire drives and uncompressed projects. If you are working in DV, then it’s not a huge deal as the data rate of DV is pretty low and doesn’t bog the system too much. There’s also less chance of sync errors on shorter clips, but this isn’t really an issue for most people anyway.
I hope this gives you a good place to start.
Jeremy