In both big and small business the life cycle of a computer is 3 to 5 years. We redeploy older systems to other usage as new systems are purchased to squeeze a little more life out of them.
Some systems get used beyond there life cycle. I wrote a program to process remote data access 800 calls for a really big drug company to collect user ID and total minutes online in order for that call to be billed back to the department that the user belong. It was a stop gap program that took me a couple of weeks to write, test and deploy.
It was to be temporary till we could get the bigger more expensive system in place to handle the processing as it processes over $500,000 in charge backs per month to departments. Well that was in 1994 and it is still in place because it worked and I left to go onto other things. I was called back in 1999 to make a couple of minor Y2K adjustments. Today I look back at that code and go, wow I could have written that in 100 lines of code instead of the several 1,000 lines I did. However I didn’t put that effort into it because I thought there was something better to replace it, so why spend the extra time to tweak it.
Another cool story: At a big drug company I installed two IBM XT 8086 PC’s in 1988 each with two fax cards. They faxed about 800 faxes per day per card orders and shipping info. The PC’s were directly connected via a DOS 3270 terminal connection via COAX to the mainframe. I finally turned them off in Oct of 1997 as they were retired and we had a newer system in place in which we migrated to. I was a proud father of those to ole PC’s as they never gave us any trouble at all for 9 years.
So the moral here is even though there is a better system, some companies do not change things.