Do I really need to $ source ~/catkin_ws/devel/setup.bash ?

Novice question: I've created a custom message, package, etc as the official tutorial does. But when i do: $ rosrun pkg_test1 pkg_test1_node it gives me: [rospack] Error: package 'pkg_test1' not found Indeed, if i do: $ source ~/catkin_ws/devel/setup.bash the problem is fixed. But do i really need to do that every time i want to use my custom programs? Is there any simple way to mantain them in the ROS path (i think that is what i am doing when i call these commands). Thanks in advance.