Release early, release often
ImageJ subscribes to the "release early, release often" mantra often cited in software engineering circles. In particular, and especially because there is a small core development team, the project is driven by Boyd's Law of Iteration: speed of iteration beats quality of iteration. That is not to say that we do not strive for quality—we do. But we have found through experience that more releases, together with guiding user feedback, push a project forward more efficiently than very slow but carefully considered and tested releases with little user feedback during each testing phase.
Do it in public
ImageJ and SciJava are not open source software products—they are open source software projects following an open source development process. ImageJ is funded by taxpayer money, so the project strives to be as transparent as possible, by [doing it in public!