i have 121.5 programmed on every system in my mobile scanner and ALL the time i hear pilots checking in, always commercial, and without an emergency; is that normal?
Yes, very normal. As mentioned by an earlier poster, 121.5 is correctly referred to as "guard" not "an emergency frequency".
It's a 'guarded' frequency that has been established worldwide, and everyone monitors it. Air traffic control units and most aircraft with more than one radio are always monitoring.
It is used far more often to communicate with aircraft that have somehow strayed onto the wrong frequency, and ATC cannot get hold of them on their assigned frequency. If they are listening on 121.5 the controller will probably be able to get through to them and get them back on the correct frequency.
There is no 'law' reserving this frequency for emergencies only. If you are constantly hearing aircraft checking in, I'd assume 'finger trouble' by the pilot, as he has probably selected the wrong radio to make his transmission after having just changed one of the radio frequencies to his newly assigned ATC sector.