I tend to as the Dutch, because at some point you're going to have to obliterate the Royal Navy and conquer England if you want to really rake in the ducats, and even with Dutch income + naval forcelimits you'd have to be crazy to go up against the Royal Navy without a top-quality leader - which the +2 naval leader fire from your NI helps you to get. So too, arguably, for Portugal, although there the benefits are less obvious because your admirals will probably not be as good and you don't really need to fight England/GB as often/at all.
For anyone else (like the Malayans and Spaniards in particular, who have the income to do this) I just make sure my navy is bigger than anyone else's and use an explorer instead of an admiral, although I will sometimes keep a dedicated admiral after I have the two special military buildings at Tech 19 built and am at 25 or more PP.