The figure will vary somewhat depending on things like dev experience, previous coding practices, automated testing etc, but there is a corpus of research that suggests that a ballpark figure is somwhere around that 40% is about right. Here's what Perplexity says about it https://www.perplexity.ai/search/what-evidence-is-there-that....
Seems plausible here, particularly if allow for the often considerable additional preemptive Maintenance effort required trying to avoid breaking the existing product while adding new features.
Seems plausible here, particularly if allow for the often considerable additional preemptive Maintenance effort required trying to avoid breaking the existing product while adding new features.