edinburgh for 4 or 6 days?

traveling to scotland in may. we have edinburgh planned for 4 days, a 2 day drip along the highlands, and were gonna spend our last 3 days in glasgow. however, im getting very excited about everything to do in edinburgh, and am wondering if we should just go back to edinburgh for our last 3 days but just go to glasgow for a one-day trip. it seems there is much more to do in edinburgh than glasgow but also hoping to not cut glasgow too short with just a day. what do you all think? thank you kindly