Here I am Gertabelle!
Our abbey typically combines Sext and None. Those are the only two hours normally combined at the abbey. As you mentioned, the hymn from the appropriate time of day is used, and the psalmody is combined. Then the readings and collect are from the appropriate time of day. On normal ferias this hour is chanted at 12 noon. On feasts and Sundays, the Mass is longer (it starts at 11) and the hour is moved to None at 3:45 pm as lunch immediately follows the Mass.
On Thursdays, it is the monks’ recreation day (day off) and they have the day off until 7 pm. On Thursdays then, Vespers is chanted at 7 pm instead of 5 pm. Compline is said immediately after but as a distinct office (i.e. back-to-back, not combined). On other days, Vespers is at 5 pm and Compline at 7:45 pm.
My own practice these days is to use the 4-week LOTH (mainly because the chant books are so much more convenient, all day hours are contained in a single volume whereas in the monastic, I’m flipping from hymnal, to psalter, and on memorials and feasts, to the antiphonary as well and it rather ruins the fluidity of the liturgy). I combine Vigils (Office of Readings) and Lauds into “Matins” and start at around 6 am. This mimics the ancient tradition of praying Vigils during the night, when it would end at daybreak with Lauds (which at that time meant the three “laudate” psalms, 148-149-150).
The formula to use is:
-Invitatory (on weekdays I like to use Ps. 66(67) because that psalm traditionally was always the first psalm of Lauds in the monastic Office)
-Hymn (you can use either the one of the Office of Readings or that of Lauds; I go by preference, and mostly but not always the one from Lauds)
-Psalmody of the Office of Readings
-Verse and response from the OOR
-First long reading & response
-Second long reading & response
-Te Deum (if called for, i.e. feasts and Sundays except Sundays of Lent)
-Psalmody of Lauds
-The rest of the Office follows the formula for Lauds.
The Rule of Saint Benedict allows one to shorten the long readings of Vigils (OOR) on summer weekdays (for St. Benedict, in the Rule it meant from Monday following the Octave of Easter until Nov. 15th, but in Canada our abbey does it up until Sept. 15th; calling November 15th “summer” in our part of the world is a bit of a stretch). This was done to accommodate the shorter nights of summer so Lauds would finish at sunrise. On Sundays and feasts however, there is no such concession.
Technically I think it is possible to combine the Office of Readings with any hour more or less as above (but omitting the Invitatory if not combining with Lauds), but it’s more typical to combine it with Lauds in the morning. The other hours can also be combined with the Mass. This is very frequent in monasteries. A monastery in France I visited combines Terce with the Mass; S. Anselmo in Rome, where I spent a week last November, combines Lauds with Mass.