I use a local php.ini file to set the include_path on my shared hosting account. I have heard (years ago) that it is the best practice to use the server default file and edit that as needed, rather than to include a blank file with only the variable that one wants set. Is this still the case? Or is it fine to include only that single variable? The drawback I had heard years ago was that if you don't include all the variables it will default them to the standard defaults rather than to the server defaults.
php.ini files are problematic as they replace all variables on the server to the factory values, I'd recommend .user.ini files, they only override the variables you've placed on them but you have to ask your host if they have enabled this feature.