Very interesting responses. I think I might need to consider these...

I use the prewound Masterpiece bobbins in my Janome Jem drop in. I take the paper sides off and just have the thread. The bobbins are wound with perfect tension so will stay tight all the way to the end.

I use them and like them for all the same reasons as everyone else. I don't think it is being lazy at all. I find it is cheaper than using up my thread to wind on bobbins.

I use cotton Bobby Cots in my Brother PQ1500s and Pfaff's for quilting. I use Fil-Tec poly in my Brother PC6500 for embroidery. All my machines take L size bobbins. The pre-wounds have all but eliminated tension issues. The only way I would not use them is if I have to color match.

I know a lot of people love them, but I'm not a fan. I bought them for my longarm and found that the bobbin tension didn't remain consistent. I tried several and this was the case with each one. I have never had that problem winding my own. I have never tried them in my domestic machine so can't speak to those type of prewound.

ive heard good and bad... I personally have never tried but a fellow quilter with the same machine i have just LOVES them and that all she uses.. and quite honestly, i dont know why i haven't tried them.. Guess i dont think about it until i read about them.. lol..

If they are on sale I buy.
Like grey ones, they work with most spool colors.
Sure are handy when you need a quick change.
But now I have a machine that uses the green bobbins so cant use them anymore.

my thought on prewound bobbins they are a great time saver but the same as pre cuts (jelly rolls, charm sq, and such) they are more expensive than winding your own. But remember they are getting much more thread on the bobbin so it not only that you do not have to wind your own but you do not have to change the bobbin as often

Do you have to worry about size or if they fit? My machines won't take the skinny bobbins, so I have to use the one that are just a bit "taller". Do the prewound ones come in different heights?

I didn't know those existed. They're probably very convenient...no stopping to wind the "bobby."