Both daily and weekly stock charts should be studied. Weekly charts are particularly helpful in providing a longer term perspective, and can offer insights regarding the quality of a base. They can tell you, for example, if there was accumulation or distribution in the base formation. Also, weekly charts can be a better option for identifying a late-stage base. Daily charts provide a closer focus than weekly charts, and should be used to determine the appropriate pivot point.
Both types of charts reveal common signs of weakness, such as decreasing prices on high volume, exhaustion gaps, or new highs on low volume.