Hi, I know your post is old but I'd like to share with you that my Grandfather currently has 21 stents.
My husband had 14 in a matter of a 3 week period, apparently one had a huge tear when they tried to stent, so instead of a bypass, they just stented the whole thing.
Like ed34, I have eight stents, and like you, I have the 'full metal jacket'. I've had some of the stents twelve years. Recently two new blockages were discovered, and it wasn't possible to get stents through the metal tunnel, so to speak, so I ended up with the bypasses. My stents served me well for quite a long time. My suggestion is to do aerobic exercise in addition to your obvious physical work, don't smoke, and eat a cardiac-healthy diet and don't worry about which is best. If you have further problems, it will take care of itself.
I've had 8 stents and a triple bypass. My triple bypass only lasted 3 months, so there's no guarantee with anything. Once your arteries are full of stents, you can of course have stents within stents.
Just on a side issue, I met 2 guys at cardiac rehab on wednesday who have bio-degradable stents. They completely dissolve away over a few months leaving nothing behind. If you have those, I suppose there's no limit.