If you're renovating a bathroom and cutting out some of the old sheetrock with a reciprocating saw, it's probably not a good idea to get overexcited at the relative speed with which it cuts (as opposed to the old-fashioned manual way you were previously cutting/smoothing out the jagged borders of the old sheetrock with a hand saw).
If you do get overexcited with the relative speed at which it cuts, at least have the good sense to be cutting in areas where you can do no real damage. Try to avoid areas where water pipes might make an unexpected jig and be lurking. Because, you know, it'd be really, really stupid (and ultimately expensive and mood de-enhancing) to cut through the water pipe and send binary compounds that occur at room temperature as a clear, colorless, odorless, tasteless liquid jetting everywhere.
That is all.