This all depends on the product used: if it is done with semi transparent stain then it should be maintained with a new coat of stain every two years. If it is a solid deck stain you will likely need to re-coat after 4 years but may get as many as five years before needing to re-do the deck.
The most common paint used on walls for both residential and commercial is eggshell latex. This type provides washability, scrubability and durability for normal usage. Semi gloss and higher sheen levels will provide greater durability. The higher the shine the more durability. There are some flat paints that provide washability and durability ( insure that the manufacturer state that it is washable and scrubable) but most are not and are not recommended.