I paint it with a paint that lasts 20 years. If it needs repainting, I prefer to take it off, replace any bad wood, and repaint before reinstalling. I think unscrewing a few screws is worth it, you can paint it so much quicker, and you don't need to be so careful about making a mess.
Now sure how big your house is but It would take me some time. I scraped, primed and painted it. I suspect the person who sold us this house did a half ...... job of it. We've been in the house for only 8 yrs.
20 year paint would probably be sufficient for the time that I have left.
Well now I expect it might be the same for me, but I hope for a bit more than 20. As long as I can handle it of course. Whatever the good lord's willing to give me.