Yes, they are all pinus strobus. Tips? Over about 17 years or so of work I have to admit that I must have tried every technique in the bonsai world and a few from the underworld. And I still haven’t found the holy grail. I will try Ryan’s approach to single flush, long needle pines and see the reaction.
One thing I can say for sure, that restricting growth - overtime - leads to some level of ramification which leads to needle size reduction. Keeping the trees alive, keeps you in the game and restricting techniques (whatever ones you choose) lead you to ramification and needle reduction. Some techniques maybe better than others and work with quicker results. Generally, I have used Japanese white pine techniques on pinus strobus. As I recall, using low fertilization during the growing season but amping it up after the new needles harden and in the fall, (It seems to make horticultural sense to increase fertilization after needle hardening as the tree starts producing buds for next year. That plus some pruning could be the best time to trigger back budding. What do you think?) bud selection and breaking candles. I have used large soil particle sizes 3/16-1/4" and no organics. I learned much of this from Boon. But getting bud back has been difficult. Still a work in progress but a good pay off is not a pipe dream.