I carry IWB all day, every day. I find that I have to sometimes move the gun a little forward or back during the day depending on what I am doing. For instance, if I am going to take a nap on the couch I will move it a little forward. Also, it is easier to carry in a holster with forward cant (FBI cant).
A gun that is carried too far back will poke you in the kidney area while seated in a chair with a back and that will never be comfortable. My usual carry position is close to 3 o'clock. My cover garment is an untucked shirt and when belted into the car I make sure that the shirt is over the seatbelt so that the gun can be accessed.
Bill