I recently read about support and resistance levels. The basic idea is that if it is the case that a stock usually rises when its value descends close to a certain number, we call that a support level. When a stock usually falls when its value ascends close to a certain number, we call that a resistance level.
These levels are often at whole number intervals as a result of traders placing limit orders a whole number prices.
My question is, on what time scale do these rules apply? Do these rules apply on an intraday basis? What about weeks, months, and years?
Edit: Yes, I realise that it is a commonly observed pattern, not an unbrekable rule.