This is a lot of time in all these cities, in contrast to the more common first-time itineraries we see that don't allow enough time. You're lucky to have more than a month. I agree that six days is a lot for Segovia, unless you plan to use it as a base for exploring elsewhere. And I don't understand ten days in Toledo with two day trips into Madrid. Will you be staying with friends in Toledo, or have a great lodging deal there? Madrid has a lot to offer, especially art museums, but even a lot beyond those. Most travelers with the overall time you have would give Madrid a week and Toledo two or three days (not as day trips). And you might consider adding a couple of days in Cordoba to your plan, easily reached between Madrid and Seville.
Do you plan to have a car for any of this trip? It would be a liability in Barcelona and Madrid, but could help elsewhere. Driving between Granada and Seville would let you see a lot of Andalucia. Driving various places from Segovia would make sense. However, Spain has good train service to all your destinations.