It really depends on the artist how long the gap would be in between their albums. Some artists take longer than others for various reasons. It's not laziness to take a long break because that actually helps you grow as a person and as an artist, which in turn will help you develop a solid body of work. I'd rather wait for them to be fully ready than to release a half-baked album full of microwave hits, especially for an artist like Adele who really pulls inspiration from her life experiences.