Hi Art,
Thank you for pointing this out! According to law the D7 visa holders are allowed to be absent without reasonable reasons from Portugal for maximum six consecutive months or eight non-consecutive months within the validity of their residency permit (I have now edited my previous post as well). According to that, spending 6.1 months in Portugal per year would not be enough.
The law also states that the residence permit is not canceled for citizens who are absent for periods longer than those mentioned before, when they prove that, during their absence from the national territory, they carried out professional or business activities or activities of a cultural or social nature. I would recommend checking with a lawyer how this has played out in practice, if you could use it in your favor.
You can see the law here, article 85: https://dre.pt/dre/detalhe/lei/23-2007-635814
