Too many points are impossible to absorb at once. They also force a slide to be on screen too long, draining energy from your presentation and your listeners. Keep to a maximum of five bullets or eight lines per slide, and confine each slide to one concept. Expand a lengthy subject to two slides, or reorganize the bullets by topic, each with its own slide. Too much information.
Information overload is particularly easy with data.
When you let yourself get caught up in statistics and labels, viewers will lose sight of the main point - or may miss it entirely. Choose the one point you want the audience to get and delete all other material as irrelevant. You can fill in supporting statistics orallys. Slides that say nothing to the audience. Long or meaningless titles.