Before I started I had no real idea what a "typical" day in the saddle would be like. If you examine the map of the Via de la Plata you will see that towns, somewhat spookily, are all about 80 kms apart (mas o menos). Therefore if you want to stay in good hotels, it is that 80 km that sets your daily run.
In the event I discovered that I could manage 80 kms a day without effort (well the first few days were a bit grim, ending the day saddle sore and exhausted), and on occasions got up to 100km in a day, when needs must. Mind you it pales into insignificance when you look at Tour de France stats, where they will do 200 kms in a day at around 3 times the speed I managed.
I found that around 5 hours cycling a day at an average speed of 16kms per hour was about par for the course for me. Included in that is around half an hour for lunch and snack stops. If you are staying in hotels in Spain, be advised that breakfast will only start 9 am on average (some did start at 8.30 am, but others were 9.30am). So I tended not to get going till around 10 am in the morning.
I set out with around 3 litres of water, as even in late September Andalucian and Extremadura can get hot, plus fruit and bread for lunch. By tanking up with a big breakfast and having a large dinner, lunch on the road was just a way of topping up the calories and taking aboard water. I would then have two other breaks in the day to split the time between start and lunch, and the time between lunch and the finish. All told around 30 minutes in the course of my day.
My on bike GPS computer would keep me fully informed on times, speeds and distances. There is a lot more climbing each day than I had imagined. Forget a view of a flat central plain to Spain. My daily net assents varied between just over 500 metres in a day to around 1300 metres. There are downhills to offset the climbs, but I found that long times took quite a bit out of me. 600 or 700 metres net assent was quite comfortable, but once it got over 100 in a day, then I would feel it. In addition there was some fairly serious days at the start, when I was not perhaps as fit as I was towards the end of the trip.
I would get to the hotel between 3 and 4 in the afternoon, have a bath and relax. The get out to look around the town by about 6 pm. You have plenty of time to look around the town as dinner in Spain is late, with many (read that "virtually all") restaurants opening at 9 in the evening or later. So do not count on getting to bed too early.