They rip out everything that has been proven shitty and replace it with new stuff. But how do they do it?
I have worked in a few companies and such behaviour almost never happened.
The management always wanted to maintain the old stuff and only resorted to a rewrite, when things were really really bad. "We don't have the time/money" was always the reply. But I had the impression, that a rewrite wasn't that expensive, it always went faster than the first version, without many bugs the first version had and a better structure.
I have worked in a few companies and such behaviour almost never happened.
The management always wanted to maintain the old stuff and only resorted to a rewrite, when things were really really bad. "We don't have the time/money" was always the reply. But I had the impression, that a rewrite wasn't that expensive, it always went faster than the first version, without many bugs the first version had and a better structure.