T1 ONCE: Flag 1 TRUE
T2 SWITCHED : TIME SINCE FLAG (1,10) AND FLAG 1 is TRUE -> FLAG 1 FALSE, FLAG 2 TRUE
T3 SWITCHED : TIME SINCE FLAG (2,10) AND FLAG 2 is TRUE -> FLAG 2 FALSE, FLAG 3 TRUE
T4 SWITCHED : TIME SINCE FLAG (3,10) AND FLAG 3 is TRUE -> FLAG 3 FALSE, FLAG 1 TRUE