Are there any issues with switching back and forth between standard and metric often within the same file?

I have been told, through a semi-reliable source, that it is a bad idea to switch back and forth between standard and metric, because the measurements can eventually walk off the mark if you do it frequently within the same document. Like you can get away with it once or twice but, it's something you should try to avoid.

Is this true? I assumed the conversions were 100% accurate.

SolidworksSketching