In the 11th c., what you would find would be better termed timers, not clocks. Even though they were commonly called horologia, whether they were water clocks ( clepsydra) or geared clocks, they did not run very long and were not very accurate. They would be regularly re-set from a sundial, or possibly even the simple observation of the sun's light at dawn first showing from one observation post. These timers were to regulate the day and night. For a monastery or cloister, it was important to perform all the liturgy of the hours, to have prayers at Matins at about 2 AM, Lauds at dawn, etc. There would also be tables, showing the time of sunrise and sunset over the year, so that a summer day wouldn't have stretched hours, a winter day shortened ones.

What you'd think of as clocks, running for longer periods of time, come in with the rise of cities and city workers, the bourgeoisie. By the 14th c. there were clocks that would help to regulate town life: a large clock with a bell could ring to let the maids know when they had to get up, to build the kitchen fires and make breakfast, another bell to let the weavers and spinners know when they had to begin work, a bell to let the dyers know when they could stop for the day. City life also meant regular, constant social interactions: a peasant could get up at dawn and work until dark in the fields. But how can you conduct business in a town, if you don't know the time? If you want to have a meeting with someone, how do you agree when? A town clock, ringing out the hours, made it possible to meet someone at noon, or three. So, it's within the towns that there would be more and more development of more and more accurate clocks.

There would be various advances in clockmaking- the town clocks would add features, telling people the month, the phase of the moon, etc. And spring-wound clocks would be more portable, could be something kept within a house on a shelf, and so people would not have to rely on hearing the bell of the town clock. But clocks with any real accuracy would not really arrive until the 17th c. The Emperor Charles V, perhaps the most powerful man in Europe in the 16th c., drove himself to distraction trying in vain to get all the clocks in his collection to chime the hour at the same time. Until the mid 17th c., clocks would be regularly set by sundial, with the aid of a sunrise and sunset timetable.

David S. Landes : Revolution in Time