"Is it an asthetic Japanese pruning technique fopar to leave a three way juntion?"

Having never trained under the guidance of a qualified Japanese pruning master, I can't be certain but would say no. I seem to recall seeing these on those maples that have received this sort of specialized attention.

Fan pruning of upright JM's typically involves the selective removal of branches so that the remaining ones properly 'fan' out into a series of layers. If you Google 'Cass Turnbull fan pruning Japanese maples' you should turn up numerous hits and even videos explaining the technique.

As an aside, Cass was a master pruner of any kind of tree or shrub and was a huge proponent of teaching Joe Homeowner the proper way to prune. Founder of PlantAmnesty and the author of several highly regarded pruning texts, Cass passed away suddenly last month of a heart attack. She will be greatly missed.

Thanks a lot gardengal you certainly do help a lot on this forum. I will look up Cass. It is very sad to hear though.