From "Pragmatic Programmer":
Most people assume that maintenance begins when an application is released, that maintenance means fixing bugs and enhancing features. We think these people are wrong. Programmers are constantly in maintenance mode. Our understanding changes day by day. New requirements arrive as we're designing or coding. Perhaps the environment changes. Whatever the reason, maintenance is not a discrete activity, but a routine part of the entire development process.
Hunt, Andrew; Thomas, David (1999-10-20). The Pragmatic Programmer: From Journeyman to Master (Kindle Locations 704-708). Pearson Education (USA). Kindle Edition.
Treating maintenance as a distinct activity from development is not productive. Defining maintenance as "no new features, only bug fixes" stage of the project doesn't quite work. If the software is being actively used and marketed to customers it does the project tremendous harm to draw an arbitrary line between active development and maintenance.
My advice to technology leaders is to follow what "Pragmatic Programmer" says. Do not draw the line between development and maintenance, and treat the entire process as development. Let customer requirements drive the funding and staffing levels of the project, not arbitrary decisions.
