Inc, everyone is different and has their own approach to riding these events so it is tricky to give you an absolute answer.
On a 200, there are normally something like 3 intermediate controls (not including info controls): one at 50k, one at around half way and one on the return leg at 150k.
Depending on how efficient/busy the 50k and 150k control is (or how much you want to stop and eat), you can reckon on 15 minutes to half an hour off the bike at each of these. At the half way, you may want to take a longer break, perhaps between 30 minutes to an hour. This might sound excesive but you will be surprised how quickly time goes when you're off the bike or when it is pissing down outside and freezing cold.
Assuming you don't get lost or have any visitations, you can get around a 200 with only 1 to 2 hours off the bike or less, it's up to you.
All you need to add to this is the time to cover 200k at your own average rolling speed (which I assume you already know) which will be affected by the hillyness of the ride, the weather, the wind and the time of year you do the event.
H