As I've mentioned in my many posts, most of my instruction was done privately (or informally, as I called it)
with various teachers. I found that this one-to-one approach really suited me. I also picked up things a lot faster than I would have had I been able to attend a club.
I was a working musician at this time, so I could not go to dojos at night as I was out gigging. I never did any grading though, as I simply wanted to learn how to defend myself using Aikido. I also got some training in Aiki-Jujitsu during these years.
Sometimes, others would also come along, which allowed us to role-play
likely fight scenarios. This was especially beneficial to me, as I was soon to find out later!
I have no rank in Aikido, although I did attend a Hapkido club for a while and attain a yellow belt.
I'd say private teaching is fine.