There is no Honeywell T5 Pro.

The document, "What are the features on my T5, T5+, or T6 Pro WiFi thermostat?" states,

"Changeover

"The changeover feature (also referred to as Auto changeover) allows your thermostat to automatically switch from heating to cooling, or vice versa, depending on the temperature in your home. Resideo requires that a 1.5 degree difference be enforced between the heating and cooling setpoints when this feature is enabled to prevent short-cycling (repeatedly turning your system on/off too quickly) You may notice that your home naturally warms or cools up to 1.5 degrees past your setpoint before the appropriate heating or cooling system begins operation. This is normal."

Thanks. Sorry, mine's a T6-Pro. That was what I was looking for; however, according to the manual, I can set it from 0°F to 5°F. The installer left it at 0°F, which may be the default. Nevertheless, I can s that you don't want to increase cycling too quickly, although there's a 5-minute delay on AC cycles.

"The installer left it at 0°F, which may be the default."

Zero is the default, but setting cool to 68 and heat to 67 violates the 1.5-degree rule so the house will either cool to 69 or heat to 66 to maintain the 1.5-degree differential. If you want the thermostat to enforce 68 and 67, set #300 System Changeover to "0". #387 Compressor Protection is irrelevant. Installation Instructions.

Thanks. So if I leave it at 0°F will the system ignore it and enforce the 1.5° rule anyway? If so, I can just leave the setting it as it is now. The ISU code is #303, which increments by 1°, so I'd have to set it to 2°.

As I read it, if you set #303 to zero or 1, the thermostat will override a temperature setting using the 1.5-degree rule. If you set it to 2 or more, the temperature setting will be in effect.