Maybe good for older ones as well.
Something I have noticed over the years when people struggle with a design or their machine they never ever think of the thread itself and its age. Who would think thread has a shelf life? Well it does. Running a large order this weekend using a very off shade brown, who knows when we originally bought it and for what but it was a color we needed and sure enough when the sample we were running got to that brown we could not get 100 stitches with it shredding. First I ruled out the head by using a different head, then I checked the digitizing and nothing was off. So I used a different color suspecting the thread was old and it ran perfectly.
So when you are banging your head against a wall thinking your machine has a problem, or the digitizing is bad maybe its your thread. One way you can tell an older poly thread is by how well it holds a memory, if you can curl it up like a wire its old.
I would also recommend never buying old stock from someone, usually they are selling it because they have had it for ever or its a company that went out of business and you have no way of knowing hold old their stock is.