Search Partners tends to get left on by default and then forgotten. Google pitches it as extra reach, but partner sites usually convert worse than Google's own results, and the placement data is so thin that it's hard to see where the waste is coming from. On a small budget where every click counts, I'd turn it off at campaign level and watch the numbers for a few weeks.
The counterargument is that some accounts do get decent volume from partners, and cutting it can starve a campaign that's still learning. A lot of it depends on whether you're spending a few hundred a month or several thousand. Has anyone run a clean split test with reliable conversion data, or is everyone going on gut feel?