Can a apple IWatch passcode be time limited in any manner?

I see. Have you turned off Wrist Detection? If you have, you'll need to enter the passcode every time.

See this --> Lock or unlock Apple Watch - Apple Support

Another question. Do you by chance have tattoos on your wrist where the watch sits?

I have owned just about every model Apple Watch and have never had one reset the passcode unless I chose to change the passcode. Please explain what you mean by a time limit? By chance is your watch provided by a school or employer, who may have Mobile Device Management installed on the watch, which requires passcodes to be reset on a regular basis?