I was able to find this in the forum
It seems Stone pine, Pinus pinea, is a two-needle multi-flush pine. So you should be able to get most of your answers by watching streams of multiflush pines, Japanese black pine is probably quite close to as Stone pine.
This rather lengthy book chapter also seems to confirm that Stone pine is at least capable of multiple flushes. Here’s a quote from the book:
“Like most pines from temperate climates, stone pine is normally
uninodal; each apex elongates its terminal bud in a single flush in spring
(April–June) into an annual shoot that forms on its tip a new whorl of
lateral branch buds (and female cones) and the new terminal bud. This
implies that the growth is predetermined the year before within buds that
are set at the end of spring, resting for nearly one year. In dominant shoots
of young and vigorous stone pines, however, the bud can skip dormancy
and start elongating immediately after its formation, completing in early
summer a second (and rarely even a third) shoot and whorl, known as
Lammas growth.”