You can use the debugger on low level api calls to get pretty much anywhere in the codebase. If you want to find whats changing a label to "foo" you can hook into every set_Text call and put a conditional breakpoint on all label changes to break on "foo", then just go up the callstack to find the logic. This strategy works on network interfaces and file interfaces as well. I abused this on our 2M+ SLOC legacy codebase and it has saved me many hours.
Also use version control to identify the most commonly edited files in the project. These are usually the files that are doing all the work (80/20 rule) and you likely need to know of them.
If you are not familiar with HN'er Patrick 'patio11' Mackenzie, I would recommend looking at what he has written and said regarding building and running SaaS businesses.
Also use version control to identify the most commonly edited files in the project. These are usually the files that are doing all the work (80/20 rule) and you likely need to know of them.
git log --pretty=format: --name-only | sort | uniq -c | sort -rg | head -10