I'm twenty five years in and have about 15 companies now. I finish projects and move on to a new one typically at a new company. Only a couple times were leaving part way through something. Would I be seen as a job hopper?
Actually I wouldn't schedule an interview if I needed the skills for six months. I would rather hire a freelance person because that would give me more control and flexibility. Even with the ability to let someone go within 2 weeks in the first 6 month of an employment in Germany.