I change needles:

-When it looks like it's taking effort rather than being an effortless piercing of fabric
-after a large project if I think about it
-if the tip doesn't hurt my index finger at all when I press up on it

Janome takes Organ needles just fine (same manufacturer , I've heard). I use those, but I also found the titanium ones after I had a string of breakages. They really are impressive for performance and longevity (and I'm not easily impressed into spending more).

I don't have a Janome but I only change needles when I need to change sizes but I reuse the needles or when I've forgotten I have the single hole plate on and I have the wrong needle position. LOL

Thank you for all your input.

You have given me some good advice - so I won’t be changing a needle after 6 hours of stitching!

I use to change the needle after each full size quilt. Daughter told me she changes if it breaks.

I change it when I can't remember when the last time I changed it was....usually it's dull!

I think I probably used the same needle for a year on one of my older machines! But that's a little extreme. I think "every 6 hours" is a marketing ploy, just like toothpaste commercials show a person using a strip of toothpaste that's as big as the toothbrush. Ha! I'm on to you, toothpaste company!

i try to remember to change when I finish a quilt--but the problem with that is that I work on several things at a time! I listen for that popping sound or if my stitch quality is not as good, or if I remember!

Mine starts to sound a little "clunky" when it is getting dull, then I know. I have quite a few spares so I do not worry about the cost. I would think 6 hours is a bit swift.

I change often in that I use different sizes for different tasks. I also can not remember what size is in there so I use a tiny sticky note and write the date and size and stick it to the side of the machine. That way, if stitching doesn't "seem right", I can check when I last put a new one in and determine if that is the main problem or not. If I change the needle, I make note on that sticky note.

My main machine also does embroidery so I change types of needles frequently but tend to forget to actually use a new needle even though I've lots! This weekend I was putting blocks together some with lots of layers and the machine kept skipping stitches over those parts so I cleaned machine rethreaded but no change then I thought to change needle. Problem solved. My machine tends to make a thudding sound when the needle is blunt.