Hey FIB, I don't understand your question about selecting joint shared vs. joint physical custody. They are the same thing. I got the following from a web search:
Child Custody refers to the legal guardianship of the child, to be resolved either amicably between the parties, during the dissolution of the marriage or when two parents cannot agree on the custody of their children. In New York and most other states, there are two forms of custody, legal and physical custody, and, arising out of these, joint custody and shared custody (aka joint physical custody).
Legal custody refers to legal custodianship regarding major decisions in the child’s life (the child’s “lifestyle”), such as religious, medical, and educational decisions. In New York, legal custody can be granted to one or both parents.
Physical Custody refers to where the child resides. Generally, a child can live with one parent, with the other parent having visitation rights, or the child can live with both parents, generally with each parent 50 % of the time.
Joint custody is where both parents have legal custody over the child, meaning that both parents have to agree on the major decisions in the child’s life, and the child resides primarily with one parent, with the other parent having visitation rights.
Shared custody (aka joint physical custody) means that both parents have legal custody over the child, and, additionally, the parents share physical custody of the child, where, generally, the child resides with each parent 50 % of the time.
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Now if you are asking opinion on joint custody vs shared custody (aka joint physical custody) as defined above, of course the 50-50 shared solution is your best bet. If you try for more than 50% you may lose since you are the busy doctor and you are not the mother. I don't care what is said different, the mom has a clear advantage in a custody fight.
I faced that choice but even a 50-50 split was near impossible in Alabama so I took a 40-60% split or the "joint custody" as defined above. It is good since percentages are only numbers - what you make of the time is what is important. That said, I wish I had more time with my kids - at least 50%.