For example, 4.3BSD was released primarily because of the need for the improved networking capabilities and the markedly improved system performance. Of secondary importance is the issue of timing. If the releases are too infrequent, then CSRG will be inundated with requests for interim releases. Conversely, if systems are released too frequently, the integration cost for many vendors will be too high, causing them to ignore the releases. Finally, the process of release engineering is long and tedious.
Frequent releases slow the rate of development and cause undue tedium to the staff.