What is the recommended time to replace CV Axle on Chevrolet Suburban?
The axle can, and usually does, outlast the rubber boot.
Many cv joints have the boot replaced and with fresh grease go on for years.
The time to replace an axle / cv joint is usually only when it develops a fault, but if you are doing a serious rebuild then some may consider replacing them « just because »...
Really, the replacement interval on these (or any CV joint/axle) is when they break. As long as there is grease in the boot and the boot remains sealed, the CV joint/axle can last for several hundred thousand miles without issue. (NOTE: This also depends on how badly the 4WD gets abused in the vehicle. This will obviously shorten their lifespan.)
The problem is when the boot cracks and spills all of the grease (gets flung everywhere inline with the split) and dirt will then intrude as well. The joint will get dry and wear out quickly thereafter. If you keep the boots dry and clean, they can last, again, for several hundred thousand miles.
There isn't any maintenance cycle given on these because there usually isn't an issue until there is an issue. When they break, you fix or replace them.