There are more pros than cons when staining a deck. Deck stain is more affordable than paint, it protects the wood and allows the natural textures to shine through, and it can revive the appearance of your home. However, deck stain also requires prep work (sometimes days or more), carries more upkeep than a painted deck, and can fade over time if not cared for. 

Applying a sealer or topcoat after staining wood is highly recommended, though not always strictly required. A sealer protects the wood from moisture, UV rays, and weather-related issues, which is especially important for outdoor surfaces like decks and fences. It also enhances the stain's durability, prevents fading over time, and gives the wood a cleaner, more professional-looking finish. For some indoor applications, a sealer may not be necessary, depending on the type of stain used and the level of protection needed. It's always best to check the stain manufacturer's recommendations and consider the wood's intended use and exposure when deciding whether to apply a sealer.

Eggshell and satin finishes are best for porches because they sit in the sweet spot between scuffable matte and distracting high gloss. Your porch sees a fair amount of wear and tear, so you don’t want paint that’ll show every mark like matte, but you don’t want to be blinded by glossy paint in the sun either. Eggshell and satin have durability and a look that sits nicely in the middle.

Ultimately, overapplication of stain can compromise the deck's appearance, durability, and longevity. It may result in an uneven finish, with excess stain pooling, dripping, or drying into thick patches. It can also obscure the wood's natural grain and texture, detracting from the desired aesthetic. Moreover, excessive staining may not fully penetrate the wood, leading to poor adhesion and premature wear. Additionally, thick layers of stain are prone to peeling, cracking, and blistering as they struggle to bond with the surface.