My core development tenant is Never Rewrite. You will be better off iteratively fixing and improving anything that is providing value to your customers. It is common for developers and managers to say that a rewrite will fix all problems and make new development easier. These claims usually come with the added benefit of some exciting new technology.
The odds of a rewrite being better for your business and your customers are vanishingly small. Sometimes though, a team manages to deliver on a big bang rewrite. Are the results better for the business and customers?
The Yankees, yes the baseball team, executed a real life big bang switchover. They built a new stadium on a literal green field, across the street from the original stadium. The team moved over, destroyed the original, and replaced the green field.
I can’t imagine a more perfectly executed big bang cutover.
But, were the results better for the business and customers?
The Yankees Organization completed a remodel of Yankee Stadium in the late 1970s and immediately decided that their baseball stadium was too difficult to upgrade. The team rejected multiple modernization attempts in the 1980s and 1990s, only a new stadium would do! Eventually, in 2006, the Yankees were allowed to build a new stadium on parkland across the street from the original stadium.
Baseball fans, the customers, went without serious upgrades for over 25 years. The local community lost their park for 5 years while the big bang was underway.
Surely though, with 25 years of planning and an unlimited budget, the new stadium was a marvel for the fans! Nope, the seating was further from the field, the bleachers had obstructed views, and the best seats were so expensive that they went empty, even in playoff games.
But it made for great baseball right? No again, the wall slope encouraged home runs, the spread out seating killed the noise of the crowd, and the empty premium seats also blocked the fans from getting autographs.
What did they get right? Better food, more elevators, more bathrooms, and bigger seats. Oh! And everyone has a cupholder now.
Was it worth making the fans wait 25 years for cup holders?
Would iterating on seat design, restaurants, bathrooms and elevators over 25 years have been better for everyone?
Even when a big bang is successful, the results won't be better for the business and customers.
Details of the Yankee Stadium history come from this wikipedia page