Too many factors to know for sure...
For example, I run a 2600rpm stall converter in my truck (Blown 93 Lightning) with an E4OD and prefer to keep the converter unlocked below 60mph regardless of gear when using this as a daily driver. I find the lockup engage/disengage very annoying.
This was all well and good and there's no heating problems on flat street driving.
However, when towing a buddy's car and trailer, I found that I had to make damn sure to get it over 60mph to lock the converter and not drop below 45mph (unlock point) in order not to send the transmission temperature skyrocketing while pulling a grade in 3rd or 4th gear. All that slip with all that load builds a ton of heat. After that experience, I added a tow/haul calibration to my switch chip. In tow/haul, it locks the converter in every gear above 25mph and won't unlock it until 10mph.
So, my point is...you have to think through exactly what you're doing with the vehicle, how much it weighs, how you drive it, and where... Then make the decision. If my truck had no lockup converter, I'd have been pulling over and waiting to the transmission to cool half way up that grade.