Crypto Mining Part Life

I had a crypto miner that was down for a couple of days, I repaired it and when I came back in 30 minutes that durability was lower than before. According to the guide it says that parts break faster after weeks. This occured a few days in and it broke in 30 mins. Are repair kits suppose to increase life or is life suppose to be weeks long and you keep repairing to increase the durability during that time?