This is not a question on which thread to use when/where but a question on age of thread.
I've heard not to use "old" thread. I've bought thread "new" at stores and it unravels, leaves a lot of lint, doesn't sew right or breaks continuously. (Yes, I had it threaded correctly.) And I don't buy inexpensive thread.
As soon as I changed the tread, my machine (a Baby Lock) worked perfectly. This could have been the same color, same thread, bought at the same time! When I put the "bad" spool back on, same problems.

How can you tell if thread is too old (or just bad)? How old is too old?

i guess you can't tell a "bad" spool until it's not working right. on "old" thread, if you pull it and it breaks easily, then toss it.

If it comes on a wooden spool and you pull the thread and it brakes.

Let me tell you a story about thread
Several years ago I was working as a quilting consultant for one of the thread companies. The company is no longer in business but made good thread (I still have some of it)
I was visiting a wholesale company that sold the thread and was told they were getting a lot of complaints about the thread from customers. I called my contact at the manufacturer and told him about it. He said..."our thread is of the highest quality". I said "but there are complaints being voiced about the thread. He said "wait a minute and he put me on a conference call and he called someone else in the company and the conversation went like this. "Hey Clem, this is (and I don't remember his name). He said, "hey Clem remember that bad batch of thread we got a few months ago?"
So my point is that sometime new thread is bad.
As those above have said....check and if it breaks, no matter the age, then it won't work. I have old thread that still sews well and is strong. Some new thread doesn't.

Makes sense. Boy do I hate buying expensive bad thread! Thanks for the info.

I pick up thread at garage sales etc. sometimes. I have found if you pull the thread and it breaks that it's too old to use but....if you remove the top layer you'll often find the rest of the spool is still good. The dust mites will get to the outer layer eventually and weaken the thread. If it's a new spool and raveling/breaking then it's probably a manufacturing defect and I would return it to the place of purchase.

I have a large collection of thread left over from when I made clothing. I feel it is to old to risk using in a Quilt but I do use it for basting the "sandwich" together.

i really don't think 'age' has anything to do with it- it is more the thread itself- and the way it's been stored.
i've been using thread my mom bought from a going out of business store in San Diego in 1991- 20 years ago...and who knows how long it had been in the store.
it is still a good strong thread- although the supply is dwindling.
i have purchased brand new thread that was terrible- broke ever couple inches and was useless- so---it's not the age that really matters.

My machine repair guy suggests putting thread in the freezer. It has lost the moisture and then just take it out as needed. Haven't tried it yet but wouldn't hurt before you throw it out.

After some rough experiences with old thread, I pretty much throw away any that I've not purchased. Unless it's on a wooden spool, then I keep it for the heck of it----------in a big glass jar.

I've had some from stores that closed 20-30 years ago. I had one spool marked 5 cents. It was on a wooden spool, so I kept it. But THAT had to be old.