It can also depend on the program one attends. In many programs, the nursing students never take a full load of patients (often just two) and never have the full spectrum of nursing responsibilities to cover during their time as a student nurse. Heck, in most programs, you don't even learn how to start IVs and you've likely only performed certain common tasks just 2 or 3 times (foley catheter insertion, certain types of dressing changes, etc).
As an example, a student may have helped with one or two patient discharges. They may have been straight forward, just fill out these couple of forms, family and patient escort takes them away. When you start working, you now run across a patient discharge to take care of. 1) You've got several other patients with all of their own demands taking you away from completely focusing on the discharge. 2) Each facility has their own paperwork and it's likely that as a student you never worked with this specific paperwork. 3) This patient may need a social work consult or there's an unclear order that must be clarified or whatnot... something that when you were a student, the nurse was aware of and could cue you into, give you the proper forms, tell you who to call, etc... but as the nurse now yourself, you've got to stop and ask a colleague who isn't familiar with your patients, is also busy juggling all of their work and and may at times not be able to stop and help you.
Yes, there is orientation for new nurses, which is mostly no more than 6-8 weeks (which can end up being less than 15 twelve-hour shifts). More hospitals are offering longer probation and training periods for up to six months in specialty areas as it really it is everyone's best interest to allow a longer transition period.
If the clinical training concerns you, research what the different local nursing programs
offer in terms of clinical training. Don't just look at number of hours but also what's the ratio of students-to-instructor as well as does the program have a senior practicum or externship opportunities where the students work one-on-one with a nurse for a term to give them a more "real world" experience. You can also ask working nurses what their experience with graduates of different local programs and how "floor-ready" they seem as new hires.