So even if you see that your 10K line UserManager class is hurting your velocity and you are spending more and more time maintaining your AcmeDatabaseManager and AcmeLogManager, you still don't why it's taking longer or what to do about it.
Problem solving doesn't work like that. Many comparable issues have been found and solved by different people at different times, in parallel, unknown to each other.
With as many people as we have on Earth it is unlikely that one special unique problem can only be solved by one special unique person. While it might happen, it's unlikely to happen to a software developer at a small company. The problems and solutions you find there are often relatively comparable or even generic, and are found and solved by many people in parallel at the same time. While working together might be faster, it has nothing to do with the feasibility of detecting and repairing issues.