No diesel engine ever had a problem from it's fuel being too clean.
With that in mind, and after some years listening/reading several
sides to the filtering/polishing debates, plus some industrial
experience along these lines, I finally added a pump & some new lines/
valves so that we can polish (sort of) our fuel.

Sailboats don't have as big a problem; our 2 fuel tanks are 150
gallons each. The fuel currently in them was pumped in August last
year. Before that, fuel was stored for up to 4 years.... maybe more by
previous owners. A smaller tank will have less water introduced by
condensation, and will have less gunk settling to the bottom. When we
first bought the boat & got underway, I was using 10 micron filters &
changing them every day for a week or so. Now I use the 2 micron
elements and only have to change them a couple times a season.

Our system is very simple, it draws fuel from either tank thru the
already-installed double Racor filter/seperator and then pumps it back
to either tank via taps installed at the bottom forward inboard corner
of each tank. So I can transfer fuel as well; also the pump discharge
is common to the fuel supply header so it can prime any of the diesel
fired equipment. The pump is a relatively cheap NAPA 12v recip that
moves about 30 gallons per hour.

This is too low a rate to be considered "true polishing" for our tanks
but I know for a fact it is cleaning gunk out. When initially run with
clean filter elements, there is no measurable pressure drop across the
filter. After a few hours running, the vacuum gage shows up to 15mm
and the pump is laboring (flow rate probably reduced considerably
too). Change the filter element, look at all the black & brown gooey
crud! Is it "polishing" or just pre-filtering? I don't care, I just
know that we will have less chance fo a fuel blockage underway, less
frequent secondary filter changes (expensive and a PITA), and the
engine will be getting cleaner fuel.

If we were going to be spending more time around the docks, I would
consider building a portable fuel polisher with a higher capacity pump
& some long flexible pickup/return hoses. There are people out there
who "polish" fuel & fuel tanks but the usual complaint is that the
service is too expensive to be cost effective for small sailboat
tanks. If it can save you an engine failure & repairs, then maybe it's
a bargain after all. Or a do-it-yourself system need not be very
expensive.

HTH
Doug King