At 3 months on mine wiht an adequate mechanic staff mine basically never break. They get right on the edge and start sparking sometimes but never have they broken down.
I set the electric, and water stations to be serviced every 3 months. I have 4 mech's atm, 3 are 1 star, and 1 has been trained to 2. The 2 star I use for research. They seem to keep my stations running smooth. (I have 3 of each station. With 5 enclosures)