The hours of the medieval day could be longer or shorter, depending on the season.
[Sundial at the Benedictine Convent of St. John, Mústair, Switzerland, a UNESCO World Heritage Site for its well-preserved Carolingian art. The Abbey was founded in about 780 A.D. and was modified and expanded over the coming seven centuries. The tower, which features the sundial, was built in the 10th century. Photo by Roland Zumbühl ]
Ye have seen how events in Amadis of Gaul can happen at the third hour of the day, or at vespers, matins, or midday. This is canonical time, obviously.
Clock-making progressed during medieval times, but most people, including our hero, used a sundial, and all days had twelve hours of sunshine. Summer days are longer than winter days, thus summer daytime hours were longer than winter daytime hours.
Though the Divine Office (Liturgy of the Hours, or The Breviary) and its canonical prayers are more complex than we need to worry about for literary uses, and the nomenclature for its hours varied over the centuries and among churches, for the purposes of knight-errantry, this is what "time" meant to Amadis:
Sunrise, sometimes called "matins" or "lauds."
First hour: 6 a.m., prime.
Third hour: 9 a.m., terce.
Sixth hour: noon or midday, sext.
Ninth hour: 3 p.m., none.
Vespers: 6 p.m., sunset.
Bedtime: 9 p.m., compline.
Vigils: nighttime watches.