My blacksmith said, with good luck, the shoes could rest for three month.
I think in most cases they wont. Or at least not all of them!
At the moment three of my animals are shoed.
One of them lost her first shoe after three weeks. She walks a little sidewards and I think that´s the reason. The same shoe was fixed again. And lost again 6 weeks later.
The other cow lost her first shoe after two month.
The third cow got shoed six weeks ago and everything is still allright.
In general I´m very happy to have them shoed. They walk much faster and are more willing. It helps alot. In my case the one with the x shaped front legs profits most.