Type of Tile

• The type of tile you use directly affects the time period between sealer coats. Ceramic tile, for example, is immune to water penetration except at the joints. As long as proper installation methods are followed, seal every one to three years. A natural stone tile such as marble will require more frequent sealing, as it is porous and can require sealing as frequently as every few months.
  
  

Sealer Manufacturer

• As a general rule, the more money you are willing to spend, the higher the quality of sealer you'll have. This also relates to the time between coats. The more expensive sealers have higher-quality chemicals that last longer in comparison to cheaper brands. Some sealers require new coats every few months, while others can go years between. While your budget dictates which type you purchase, the frequency directly depends on the sealer quality.
  
  

Type of Sealer

• The type of sealer you use can also determine the frequency of required coats. For example, a penetrating sealer that goes beneath the surface can last longer than a topical coat that eventually wears off due to water pummeling from showering and cleaning with a squeegee or scrub brush.
  
  

Personal Preference

• Much like coats of paint on a bedroom wall, you don't need to worry about overkill when it comes to sealer. You can apply coats as frequently or as infrequently as you like, based on the type of stone, type of sealer and concerns about water penetration. Following the manufacturer's guidelines is recommended, but you can apply extra coats in between if you prefer the extra peace of mind.