My friend who is an electrician said they can be wired in above the light switch too, that way they are easily accessible. I quite liked that idea. If I stay in this house much longer I might get him to change them.
No. We check our smoke alarm twice a year when we change our clocks forward or back for daylight savings. This is what our local fire brigade has recommended. It has always been change your clocks and check your smoke alarm battery. When the newsreader tells us to change our clocks before bed he always tells us to check the smoke alarm battery. This is what happens in Melbourne anyway. Our fire brigade has never advised us to check more frequently than that, but it couldn't hurt to do so.