Our table butter is ALWAYS soft. We keep a stick on the kitchen countertop all the time. In a stainless steel dish with lid, that admits no light. It'll keep that way, at room temp, for over a week.
By which point we've used it all, and a new stick goes in. After a dish cleaning. If we have a dinner with guests a fresh stick goes into a butter dish that matches the table setting. About 2 hours before, so it softens naturally.
We didn't know that warm butter keeps so long. But a friend, who's a wizard of a chef, told us this. We haven't been sickened yet. But you should use a covered butter dish that's totally light-proof, as we do.