A shop’s opening hours are a promise made to people who arrange journeys around them.

Posted hours are not information; they are a commitment other people build a morning around. Someone times a bus, arranges cover, walks with a bad hip, and arrives at a locked door with a handwritten note taped to it. The cost of that closure sits entirely with the person who travelled, which is why a stated time carries more weight than it looks like it should.

If you set hours for anything, keep them or change them properly rather than improvising. If you cannot open, say so where people will see it before they set out. Reliability is mostly this and very little else.