I was going to add something along the lines of "for decks, porches, and patios, a multi-pass, mirror-smooth finish probably isn't the desired end result for sanding." Not to discount the value of a consistent, even result, but I've never really thought of outdoor architecture requiring significant gloss/smoothing unless it's restoration of historic Victorian detail work, in which case you're still probably stripping before sanding and then painting over the resulting work.
That's all IMHO, and as an amateur/homeowner who hasn't done this sort of thing for a living.
I don't get it, what does your comment have to do with anything I said above? ![Scratching Chin [scratch chin]](https://www.festoolownersgroup.com/Smileys/default/chin.gif)
And besides that, why would mirror smooth not be desired? Wobbly's preferred? ![Scratching Chin [scratch chin]](https://www.festoolownersgroup.com/Smileys/default/chin.gif)
It wasn't intended in contrast to your statement, but in addition to it.
In my mind, a mirror-smooth deck / walking surface is undesirable, especially when wet. That doesn't mean that a person would want swirl marks everywhere, but if you're going to be covering it up with stain or paint, you're probably not sanding a deck or patio progressively to 400 or 800 grit.
To me, a rank amateur who knows very little about things, there's something about outdoor architectural pieces like decks and patios that says "rough sand it once, finish sand it once, seal or finish it, and move on", compared to a bookshelf or interior hardwood piece of heirloom furniture that might take progressive passes with higher and higher grits, multiple coats of finish, etc.
That said, I also seriously disliked the paint job that I paid to have done on my house a few years ago. There was a rough scrape, putty fill, prime coat, and final coat (should have been at least two coats of paint on top of the primer). I wasn't as upset about the lack of second coat as the quality of the base when it was all said and done. Lap siding should look smooth, not like it had 6 different people scrape off the old paint and miss half of it along the way.
Half the time I post I'm just thinking out loud, honestly.