That's not how PE usually works.
House flippers, using the analogy, want to buy low and sell high. They typically buy a house that needs help, fix it up, and sell it. When they fix it up, they don't typically use top-notch materials or methods, they fix it up as cheaply as they can, making sure that the house *cosmetically* looks great. But they might well ignore serious, but unseen problems, like repeated sewer backups. When they sell, the house is genuinely in better shape than when they bought it. But it is not likely in *great* shape. The new owners may well find out that the house has hidden problems.
This is more like what PE does. They may genuinely improve the business. But their goal is not to make the company great. Their goal is the exit strategy: to sell for as much as possible. They will often cut staff that aren't urgently needed, but their loss will be felt over time. It's all about short-term profits rather than long-term sustainability.