Orientation does vary from one place to the next. I know of one ER that has a 4-week orientation, while the one where I work does (up to) six months.
When I started at my current job, things were so busy that I was working my own patient load within a couple of weeks. This is nobody's fault, but it makes the process less effective in the long run.
For example, I chose to challenge out of an ECG class, took the test (I am a lousy test taker), and missed a few questions on blocks and pacing. I then attended those two classes and re-took the test, and did OK. I then realized that I really should have taken the entire class because I would have learned so much. Instead, I succumbed to the "hot-dog" thing and shortchanged myself. I took the next class (meds) in its entirety, and it was a great refresher; well worth the time.
The third part of this "Core I" class is body systems, which I will also take in its entirety. I have learned to take advantage of the training that is offered.
As for the actual "hands-on" part of the orientation, my preceptor has been excellent, as have most of those with whome I work. Again, due to nobody's fault, we have been so busy (I worked three codes in my second week with very little supervision - my preceptor was occupied with other patients who were crashing) that some of the finer points of orientation were overlooked. I am working to fill in those "gaps" from this point forward.
In the long run (barring unforeseen circumstances), all should work out well, but there is really no orientation that covers everything perfectly. Fortunately, there will be continuing classes and "in-services" to keep us all up to date.
As the saying goes, "we learn enough to be dangerous, the rest of the learning comes with experience."