Agitation in film developing parlance doesn't mean shaking the canister violently but inverting it gently, or rolling it on the desk or countertop or in the sink using what Bill Pierce used to call the rolling pin method. Yes, 5 Seconds every 30 seconds was for many years considered to be the standard agitation time and interval,but there is also a method that uses 10 seconds of agitation at the top of each minute. There is also stand development, in which the developer is poured into the tank and the tank is rapped sharply on a hard surface to dislodge any air bubbles, and then the developing is done with no agitation.