I only use my thread stand that sits on the surface behind my machine. I should add that I usually use the large spools that can be ordered from Connecting Threads. Never had a problem this way.

My machine only has vertical.

Whenever I found that the thread was catching, it would usually be catching on the notch on the top side of the spool. I would just turn the spool over. Problem solved. The thread came off the spool the same way, but the notch was out of the way.

. What brand are you using? I thought that type of spool went away years ago.

It depends on the way the thread is wound on the spool. If the thread is wound very evenly across the spool, it's supposed to come off the vertical spool holder. If it is wound crosswise (higgledy-piggeldy) then it is supposed to come off the horizontal spool holder.

A good video of the concept of cross-wound and stacked thread can be found on April's vintage sewing machine website: singer-featherweight.com.

If a cross-wound spool is placed on a vertical spindle, the thread can come off kind of jerky, which can affect the tension. Since almost all vintage machines have vertical spindles, a thread stand can help in pulling the thread from the spool in an upward even motion.

I have always been told it depends on how the thread is wound on the spool. Might be true, but I have both spindles on the machine I use the most and use the thread interchangeably and on my old machines, I only have one spindle and use all threads on them. So, I don't know that it really matters.

Maybe I missed something in Dr. Bob's video but I got the impression that both straight wound and cross wound cones, which are too big for the horizontal spool, need to be on the vertical. The cones should be on a separate vertical spool besides your machine. Please correct me if I am wrong about this.

Superior thread holders can be used horizontal or vertical. Maybe he was referring to using his brand one. I haven't seen a cone of thread wound straight on a big cone though.

I agree with that, and do the same thing.