In Magento it is possible to write <script></script> and <style></style> tags and use JS/CSS directly in CMS pages, which is the easiest and fastest way to add code to only a certain CMS page.
There is also a more complicated way described here, you can add JS/CSS through the filesystem, by using layout updates.
Our Agency says that the first way is very dirty and we should stop doing it like this and instead use the second way because they want every change to appear in git.
Are both ways ok, should I listen to the Agency?