Most of the time, I like to have mostly probes, with Kerbals limited to extremely tested vehicles, or inside Kerbin's SOI for easy rescue missions. Usually, getting stranded in Kerbol orbit is a death sentence, because I am not skilled enough to dock like that. As of right now, I have only landed Kerbals safely, and returned safely on a few planets. But I think that its the most fun way, and games like this are just to squeeze out enough enjoyment as possible, not a set guideline. So, yes, I like to keep my Kerbals safe.