I am at 60 hubs. I would love to say I was on a race to the top to get to the milestone of 50, but like others who have answered, the biggest problem is finding the time to write. But I did find that after 50 hubs publishing became easier because I had a lot of different templates to use from previously published hubs. And I knew which capsules were best for me to use.
Overall, things have not changed too much, but soon will. I have a ton of ideas and the beginnings to a lot of hubs, but I just end up benching most of them until I have time to put forth a good article. Getting into the swing of consistently publishing hubs will be much easier once I don't have a ton of papers to grade. So, I will be picking up the pace mid-May.
I don't know if this helps in anyway. But the process is different for everyone. Hopefully there is something useful in this response.