Nope. Again I stated that I am quoting manufacture replacement numbers and I didn't want to get into a battle of "my drivetrain outlasts yours because I know when to replace stuff".
Actually I suspect that your drivetrain is past worn and your chains are stretching to fit (which will happen)...
Also note that riding style and area you live in also has something to do with it.
My racing bike I want to make sure is always ready so I tend to replace stuff closer to when it is "suggested" to prevent being out on a day that I want to hammer hard and don't want it to skip on me.
My comutter bike gets stuff replaced when it falls off... Well OK I change it a bit sooner than that but theres times when I ride home stuck in a certain gear because a cable froze or broke. That reminds me I'd better replace that rear tire before it pops on its own
If you do fairly casual speed riding (20mph or less) then your bike will likely last longer (given the weather conditions and stuff noted above). Here in South Florida sunlight and sever downpours are our worst problem. My comutter tends to rott cable housings and tires tend to rot off (esp on the side that tends to face the sun all day). Heck my wife's bike has changed from red to pink over the last three years! And only on one side!
Steel bikes tend to only last like 5 years if you keep them in the garage here. I converted my garage to be airconditioned and I keep my steel bikes inside ALWAYS.
A friend with a POS 7-speed thinks he gets lots of miles without changing stuff but after watching him, he is getting like 8000 miles before he starts to get chain-skip. Usually he just ignores it, as he is, but eventually he tries to keep up and ride fast a time or two and the skip eventually bites back enought that he realizes the bike is really in need of a change. Ride light and it can go a long way... Ride tough and it will wear out faster.