I know there are several schools of thought regarding browned-out fronds. One is to leave them alone. It's natural. The look is how the palm would appear in habitat. Another idea that makes a lot of sense is to leave fronds alone until they are 100% brown. No green at all. Because, the thinking goes, ANY green is benefiting the overall plant. Lopping off a frond with some green deprives the plant of the energy that living part of the frond produces. I get and sympathize with all of the above.

That said, I just can't resist cutting off brown fronds. And my tolerance threshold is low. I'd say that when a frond is 50% brown, I remove it. It's a personal preference thing. I just wanna see green when I look at my palms. Additionally, I think a case could be made that pruning off a half alive frond actually helps the plant by allowing the plant to focus its attention on the remaining fronds. By pruning off half dead fronds, the plant no longer has to provide daily water to those fronds. With other plants, we are familiar with how pruning is used to help reinvigorate plants. Used judiciously, why not for palms too?