I'm no expert, so take this for what it's worth:
I've been listening to Ken Hill's podcasts (they're free, you should check them out) on riding skills, and one of the "report cards" he uses is "how long am I at neutral throttle, and how can I reduce it?" He also explains the difference between entry and exit corners. Basically, are you trailing off the brakes past the apex, or are you cracking the throttle open before the apex? It all depends on what THAT corner hast to offer. Does it have a big straight afterwards? Well then it's most likely an exit corner, so you want to get on the throttle as early as possible to take advantage of that long straight afterwards.
I can't think of a situation where you would want to purposefully be at closed throttle in a corner. Look at videos of guys like Benny Solis at Chuckwalla. He's either on the brakes, or he's on the throttle, and MAN does he get to WOT fast. If it's an entry corner, you can take advantage of your entry speed and trail your brakes all the way to or past the apex before you're back on the gas. If it's an exit corner you will benefit more from getting your braking done earlier so that you can be at WOT as SOON as possible.
Just my $.02, I will try to find a link to those podcasts for you. They've really helped me.