What transmission do you have (6 or 8 speed)?
Fluid and filter every 24-36k for daily drivers; 12-18k for heavy duty, towing, working beyond the scope of private party ownership patterns.
Failing to change the filters in these six and/or eight speed units can result in increased contamination, them getting partially restricted resulting in inconsistent oil pickup and slippage at WOT.
The six speeds (6L45, 50, 80, 90) are also prone to pump wear on the working surfaces as well as wear in the pressure regulator valve. Keeping up with fluid changes mitigates the associated risks and helps prolong the life of these units.
The eight speeds (8L45/90) have a TSB
for TC shudder and harsh 1-2 upshift, primarily due to use of wrong fluid used. Per the link, flushing the trans with mobile 1 synthetic (or presumably any quality full synthetic fluid) helps.
The solenoids in between types of transmissions are also very sensitive to contamination, moreso than earlier units like the 4L60e.
Address pattern failures by installing updated parts and performing requisite procedures on overhaul.