You're right. NPR has just two speeds. Slow and slower, and that's a problem they're the first to admit. NPR has never been good at rapid responses to breaking stories.
One reason for that is NPR's reluctance to just "go live" with people filling time with nothing of any substance to report. They don't like to do that, unlike our TV networks, who fill hours of live air-time with mindless chatter while they wait for fresh information. NPR prefers to wait till real information starts flowing.
They also have a policy of not putting anything on the air until it can be verified by at least two reliable sources. That's why it's common for the TV networks to be reporting something that won't be heard on NPR until some time later. That's just how NPR does things, and it's not going to change. As one of their editors told me once, "We don't care about getting it first. We care about getting it right."
Aside from that, NPR brass has been struggling to improve their ability to react ever since the Oklahoma City bombing in the mid 90s, and the events of 9/11 in 2001. NPR's "performance" in the first hours after those events was pathetic and they admit it. This desire to be "quicker on their feet" is one of the factors that led to Morning Edition becoming a two-person show, which, unfortunately, did not include longtime host Bob Edwards. But that's another story.
Another unfortunate fact of life for NPR is the lack of dependable news resources at the local level. The vast majority of NPR affiliates are on college campuses, and are run by students and volunteers who don't know the first thing about covering hard news. Only a handful of affiliates have full time professional news departments.
Big breaking stories of national interest often happen and change so fast that accurate information is outdated by the time it makes air. Sometimes it just takes longer than anyone likes to get an NPR reporter, or a local professional, into position to keep up with the flow of info and provide accurate reporting. That's one of the reasons NPR depends so heavily on live telephone interviews.
So what you heard the night of bin Laden's death was what NPR was able to provide on short notice. But rest assured it's a problem they're determined to change.