Hi Steve

Very important to find a balance between what keeps you interested in continuing to practice and developing skills. There is no time line as we are all different.

And there is no harm in reverting back to a lesson if you just can't get it and your frustration level is building. This is not about a test of will power. Its about enjoying yourself and your time with the guitar.

In terms of hand speed, we all have limits. With experience you will find songs and tempos that are comfortable and fun to play. For instance, in my case I don't want to go much faster than "get off my cloud" by the stones. So that and anything slower are more fun for me.

Keep practicing and keep it fun. Things will work out.