Depends on the type of project and whether there are a lot of revisions. Client may also have a requirement. A 'hard and fast' rule may not be practical. It's often easier to modify a schedule than to modify notes on a plan if there are a lot of revisions or a lot of common pier types. You can still have P-1 TYP U/N for both plan notes and schedule and the pier type can be referenced in a foundation schedule. As a personal preference, I prefer plan notes unless the project becomes 'larger', then a schedule... the pier schedule can reference typical cross-sections as reqd.
Dik