Volumes play an important role in chart analysis. I usually look at volumes mainly in few scenarios.
First is during some kind of volatility contraction pattern, where stock price undergoes tight consolidation/compression and volumes dry up totally. If there is a breakout from this kind of a pattern, it should ideally be with very heavy volumes. ( Its very rare to see such a breakout with lower than expected volumes. )
Second is during initial stage of correction in a particular stock. When after a sustained bull run, we get a big bearish candle with very heavy volumes, it is usually a precursor to a bigger fall. Most of the times during routine bull market corrections, the corretions happen on low volumes as compared to volumes on up days.
Thirdly when there is a major breakout above a strong resistance area, say breakout from a cup and handle, or inverted head and shoulders or a rounding bottom, or above 52 weeks highs, or multiyear highs, a big bull candle on weekly charts with heavy volumes gives added confirmation.
Most of the technical analysis books will lay emphasis upon volumes along with price action. I usually don’t put up volumes in most charts I put up because it creates too much messiness in the picture. But usually I check volumes to confirm that they are in sync with pattern breakouts.