An aftertreatment system (100; 200), comprising; a first selective catalytic reduction system (140; 240); a second selective catalytic reduction system (150; 250) positioned downstream of the first selective catalytic reduction system (140; 240); a reductant storage tank (110; 210); at least one reductant insertion assembly (120; 220) fluidly coupled to the reductant storage tank (110; 210), the at least one reductant insertion assembly (120; 220) fluidly coupled to the first selective catalytic reduction system (140; 240) and to the second selective catalytic reduction system (150; 250); and a controller (170; 270) communicatively coupled to the reductant insertion assembly (120; 220), the controller (170; 270) configured to instruct the reductant insertion assembly (120; 220) to asynchronously insert the reductant into the first selective catalytic reduction system (140; 240) and the second selective catalytic reduction system (150; 250); wherein the reductant insertion assembly (120; 220) includes: a first injector (123; 223) fluidly coupled to the first selective catalytic reduction system (140; 240); and a second injector (125; 225) fluidly coupled to the second selective catalytic reduction system (150; 250); and wherein the controller (170; 270) is further configured to: (a) activate the first injector (123; 223); (b) maintain the first injector (123; 223) activated for a first delivery time for inserting a first amount of reductant into the first selective catalytic reduction system (140; 240); (c) deactivate the first injector (123; 223); (d) immediately after the first amount of reductant has been delivered to the first selective catalytic reduction system (140; 240) and the first injector has been deactivated, activate the second injector (125; 225); (e) maintain the second injector (125; 225) activated for a second delivery time for inserting a second amount of reductant into the second selective catalytic reduction system (150; 250); (f) deactivate the second injector (125; 225) and, immediately after the second amount of reductant has been delivered to the second selective catalytic reduction system (140; 240) and the second injector has been deactivated, return to step (a) and repeat steps (a) to (f) in a loop. a first injector (123; 223) fluidly coupled to the first selective catalytic reduction system (140; 240); and a second injector (125; 225) fluidly coupled to the second selective catalytic reduction system (150; 250); and wherein the controller (170; 270) is further configured to: (a) activate the first injector (123; 223); (b) maintain the first injector (123; 223) activated for a first delivery time for inserting a first amount of reductant into the first selective catalytic reduction system (140; 240); (c) deactivate the first injector (123; 223); (d) immediately after the first amount of reductant has been delivered to the first selective catalytic reduction system (140; 240) and the first injector has been deactivated, activate the second injector (125; 225); (e) maintain the second injector (125; 225) activated for a second delivery time for inserting a second amount of reductant into the second selective catalytic reduction system (150; 250); (f) deactivate the second injector (125; 225) and, immediately after the second amount of reductant has been delivered to the second selective catalytic reduction system (140; 240) and the second injector has been deactivated, (a) activate the first injector (123; 223); (b) maintain the first injector (123; 223) activated for a first delivery time for inserting a first amount of reductant into the first selective catalytic reduction system (140; 240); (c) deactivate the first injector (123; 223); (d) immediately after the first amount of reductant has been delivered to the first selective catalytic reduction system (140; 240) and the first injector has been deactivated, activate the second injector (125; 225); (e) maintain the second injector (125; 225) activated for a second delivery time for inserting a second amount of reductant into the second selective catalytic reduction system (150; 250); (f) deactivate the second injector (125; 225) and, immediately after the second amount of reductant has been delivered to the second selective catalytic reduction system (140; 240) and the second injector has been deactivated, return to step (a) and repeat steps (a) to (f) in a loop.