title_body: Does longer brewing time with hot water negatively effect flavor?
upvoted_answer: As discussed further in this question about bitterness, degree of extraction is one significant factor in bitterness in your cup. There are a couple of other links to coffee bitterness in that question also.
  
  Keeping other major factors constant (e.g., same temperature of water, same beans), time and grind level are the easiest to modify to reduce bitterness. That is: shorter time and coarser grind will (generally) result in less bitter coffee. While you certainly can't expect to get a reasonable brew from barely chopped beans in 15 seconds, small changes in time and grind level can have a noticeable impact on outcomes, especially for immersion-style brewing methods like French press, Aeropress, pour-over, and to a lesser extent stovetop methods like percolator or moka.
  
  Specifics vary by brewing method. For instance, some bitter-tasting compounds are filtered out by paper filters, so paper-filter pour-over will generally be less bitter than French press, for example. Also, your average paper filter will allow brewed coffee to filter more quickly with a coarser grind (finer grinds will more quickly clog the filter) so you might have to vary your pouring method to keep the total brewing time constant.
  
  You might enjoy trying to vary one parameter at a time: trying coarser- or finer-grind coffee, then with a shorter or longer period of time, in both cases trying to vary only one parameter at a time.