Please don't have this attitude. Learning how to do an assessment is a critical nursing skill. Depending on what speciality/area you go in to, you will find yourself losing certain skills and relying on others. That doesn't mean you don't need to know the basic idea of how to do an assessment if something unusual pops up.
I work adult med surg. Once in a blue moon we get a pediatric patient. About once every 6 months we get a pregnant woman. Each time I have to reach back in my knowledge and remember what I know about these patients, because these are not my norm. Same true if we happen to get a hip/knee, women's surgical, or neuro patient (none of which we usually get). You will always have a chance of getting "overflow" specialty patients, or being floated to a speciality department.
As for your original question- the most thorough assessment I do is on admission. Head to toe, to butt cheeks and between those toes. I am so fast though, that an observer may not see everything I am doing or realize how thorough I am. I couldn't have developed a fast way to do this if it weren't for my basic knowledge I was thought in school. When necessary, I focus on one body part over the other (the complaining/problem area). This takes me around 30 minutes including med rec, history, ect (all of the required facility charting). I do my focused shift assessment in less than 5 minutes on each patient. I am also constantly assessing my patients throughout the shift, though they usually don't realize this.
As for not using an otoscope... I had to do that recently!!! You never know what skills you will need on a given day.
ICU nurses do the most in depth assessments, my guess.