The recommended rebuild interval may be 20K miles. Unless you blow a seal or loose gas pressure I think you can go longer. Front Ohlins for my '05 GS came off the bike after 44K miles because I had a second rebuilt shock sitting in the garage. It could have gone longer. The rear Ohlins, on the other hand, needed a re-build after 34K miles. It was still working, but not as good as when new and I found myself tweaking the damping more than should have been necessary.