I like using cardboard with target stickers. This makes measuring group size with the app I use. Yesterday I was out trying my new pasture range I put together. I did use a paper target with the 308 Win. , I wish the paper didn’t tear out around the holes.
I like both of those. I tend to use whatever is around, though cardboard is likely the most common. For handgun, there are a few brands of paper plate which are a bit heavier and throw off a plug of fiber when hit.
Of course, there's always fruit, but that usually comes after the zero process. 0
I use paper targets that I print, and then staple them to cardboard for a backing.
When I get home, I mark the date, rifle, load, velocity, etc, punch them with a 3-ring punch, and put them in a notebook. That makes it easy to follow load development when you pick it up 3 years later.