It all hinges on you knowing the appropriate things to ask and examine for the given situation. As a rule you generally want to give stuff in the right order. I would say always be prepared for a full formal presentation, but abridge it as needed. Know more, say less.
For follow up visits and well checks, most of your hpi will be pertinent negatives. Obviously you need to know what these are to do this well. For acute issues your hpi will be a little easier as you basically recite the pertinent aspects of a story. The key is summarizing the findings. Patients will give you 2-3 minutes on something that can summed up in 3 seconds.
For the exam, as a student you'll want to do a pretty thorough one since that's the whole point of your learning. As a rule, describe what you see or don't see/hear/feel, but don't say "benign" or "normal" because nobody believes you know what that means yet.
Give important labs, imaging, etc. Give your own findings and don't just repeat the formal read. As you go along, you'll learn to put some of this at the top (most recent A1c for diabetics, last EF for CHF, etc), but avoid the habit of reciting the entire past history before the HPI.
For the assessment and plan, make sure you don't give this away earlier. Most common problem is students editorializing through the whole presentation. Just recite the facts and save your thoughts for the end. Ask your attending how they like this part done as each will be different.
Overall, this gets at the very crux of medical education in that you're learning the language of medicine and how to communicate effectively with other physicians. I learn more about this every day in residency and don't see the learning stopping any time soon.