I voted 3 because normally I sleep with 2 under my head, and one that I sometimes use for my back. However, my husband came home from the hospital a week before Christmas and we are dealing with major health issues. Friends of ours had a hospital bed that is now in our living room because he cannot do the steps at this time. I’ve been sleeping in the recliner next to him. So, presently, he uses 2 and I’m using none,
3; having my body too flat while I sleep gives me acid reflux.
Two or three depending on use/season.
One always for general neck support (90% of the time I’m a side sleeper, occasionally back), one contoured memory foam pillow between the legs (reduces knee pain for me and cools), and during the summer, often another head pillow to swap to if the first gets too warm.
Gonna say >4, since the ginormous body pillow my husband bought me counts for at least 4 on its own and I also have a pillow for my head, as I use the U-shaped one upside down. Yes, I suppose I’m a delicate flower… 
Knee knocking is the worst. I use a body pillow to prevent it as well as to provide an arm rest.
For sleeping - none. I use a pillow when I go to bed to read for a while. When I decide I’m too drowsy to continue (not very long) I slide the pillow to a shelf on my nightstand. Then I just lay flat and I’m asleep in about ten seconds.
I said one, but I rarely use the whole pillow. I’m a side sleeper and usually have my head on just the lower quarter of the pillow.
This describes my pillow use.
I avoid this by going to sleep with one leg bent, like Captain Morgan or a lower-case letter “h”.
For the cats, of course.
There are usually two pillows on my bed; but I sleep on one or half of one, the additional pillow space (as well as some additional bed space) usually being taken up by felines.
No cats. But this entire discussion reminds me of my MIL’s pillow preference. She has a pillow that has almost no stuffing in it whatsoever. I mean, it’s pancake-flat. She has been known to fold a washcloth into quarters to use as a pillow.
Two, but they’re both small.
Just 1, I hate an oversupply of pillows, like in hotels and BnBs
When i hike, i roll up my rainjacket to make a very small, very hard pillow.
Interestingly, I come from a country that uses wood pillows, not that I do.
My grandfather used to use a section of log as a pillow. The whole thing was about 8” long and perhaps the same diameter, and polished smooth, with one side cut flat so it wouldn’t roll. He used to rest his head on it while lying on the floor watching TV. It was surprisingly comfortable. He didn’t sleep on it, other than if he fell asleep watching TV.
Off and on for years I’ve used a buckwheat pillow. Which are apparently a traditional Japanese invention.
Anyhow, their claim to fame is they’re infinitely moldable, but pretty rigidly stiff once arranged. So not cushiony at all. The bag containing the hulls is much larger than the filling, so you can rearrange it into lots of shapes. They’re also much smaller than traditional western pillows.
Moosh (technical term) it around until it’s holding your head where you want it, then let go and there you are, head & neck all cradled securely until you need to roll over or whatever. The just re-customize the shape for your new posture.
Two. And they must be down, not whatever that foam stuff is.
Two. I like the extra-firm side sleeper pillows, not stuffed with down (too smooshy). One under my head and one between my knees. And I deal with the acid reflux issue mentioned above by elevating the head of my bed on two risers. Boy, do I miss those risers when we travel and I sleep in a strange bed.
1 for me and 1 for the dog. Amazingly she hasn’t tried to shred that pillow, but the throw pillows on the couches downstairs are doomed. 2 already shredded, and 4 with little nibbles taken out of the corners.
I love my My Pillow which I purchased long before they became a political hot potato. I moosh it every night and it stays the way I like it. It did take a few days to get used to the texture.
At least, unlike your Tesla, you don’t need to embroider a sign on your pillowcases saying “I bought this before Mike went nuts!” 
@LSLGuy, you’re totally missing out on a business opportunity! Make that into an iron or sew on patch and sell it to MyPillow owners who are now sheepish about it. You could make tens of dollars before a big outfit pushed you out of the marketplace!