I bought my 3rd as a companion but was going to end up with number one pony retiring soon so bought one the same age as number two so they could be life long companions. Both of those are also ridden and number one is now retired.
I have three for this reason... but they all work, so they are all also companions! The third was free, and I didn't know if he would be rideable, but he has turned out to be a pocket rocket. Don't know if that is a good thing or not really, it's quite a lot of work....
We did, we had a companion given to us that would turn herself inside out when daughter and I hacked out, so we got a WHW pony. She went back this autumn as I am pregnant and my mare has almost retired. If we get anything else it will be a 1st ridden for my 3 year old daughter