Steering cables seem to last from on average 5-7 years. If yours are still good and say 10 years old, well then you have gotten your monies worth. As for shift and throtle cables well the control box can be the problem as well as the cables. I have seen allot of control boxes worn out and shift and throtle cables that sretch and won't work properly. The fastest way to ruin a shift cable is to try and shift it into gear without the motor running. The clutch dog (shifter) and gears in the lower unit have lugs or teeth that lock together to engage the gears and it they line up tooth on tooth and you try to force them into gear it can damage the shift cable. As for slop it the cables when giving it throlte most times the cable is moving the trigger or timer base first before the carbs start getting opened up, the timong on most motors advances first before the throtle plates start to open. Inside of a control box can be a nightmare if you don't know what your doing and it may cost more in the long run if control box or lower unit get damaged due to cables being installed or not adjusted correctly.

Tom