Since when?!

Conclusion: Is Three-Day Room Temperature Butter Safe?
In conclusion, while my mom’s practice of leaving butter out at room temperature is common, it is important to be cautious. Salted butter may still be safe after three days, but it is advisable to check for any signs of spoilage before use. For unsalted butter, refrigeration is recommended if not consumed within a day. Ultimately, the safety of room temperature butter depends on several factors, including the type of butter, storage conditions, and personal tolerance for risk.