I have owned two different HST pedal configurations. My old IH had seperate forward and reverse pedals operated by the left foot. My current Power Trac has a treadle, with the right foot you go forward, with the left you go reverse. Pushing either pedal causes the other to rise. Several Kubotas that I operated had the treadle on the right foot, with toe push moving you forward and heel push moving in reverse.
None of the HST tractors that I operated had cruise control, so, yes, if you need to stay at a constant speed for a long time, you have to keep your foot on the direction pedal the entire time and it could cause exactly what he stated: shin starts to hurt.
I only found that problem with mowing large fields. For any operation that requires frequent speed or direction changes, like mowing around landscaping, trees, snow plowing, front end loader work, brush hogging, etc... I never noticed any shin pain when operating an HST.
Hope that helps.