Google?
Thankfully, there is nearly always an overlap period when one solution gets deprecated and the replacement is launched.
The COVID19 office shutdown has really focused attention on our internal IT tools (most of which are also offered externally). So far, they've worked pretty great, in no small part because things like BeyondCorp [1] were designed from the start for distributed workforces in zero-trust security environments.
It wasn't always like this though. Corp-Eng, as it's called at Google was for a long time seen as a dead end career-wise - disconnected from Google's marquee products. However, a number of developments, including the rise of the enterprise and cloud computing businesses, have bolstered its internal importance, and with that have brought excitement and talent to the organization. It's now an important source of product feature ideas that eventually make their way to customers.
That said, a lot of things not core to Google's problem spaces do get solved with outside vendors' software, and some of that software is great. For example, I just used a site licensed version of the Chrome ScreenCastify [2] extension to make a video demonstrating a feature I'm developing. It worked perfectly.
For example the code search, testing, code review tools are amazing and better than any commercial equivalent.
Other tools like the bug database are on par with the industry.
Others like the food, directory and interviewing tools are still pretty damn good and even if they are lacking some polish, are often far more functional than the average commercial equivalent.
And of course they are hit and miss - because there are so many of them. The ones that are commonly used are well funded and have lots of people working on them.
I no longer work at Google but still consider it a role model for how companies should take tooling seriously.