Hugh, the sheer number of churches and other monuments — coupled with my firm insistence that a bunch of photos thrown online is not only not a website, but it's not even terribly interesting or useful — makes progress on my site very slow. On my "churches" pages, for almost every thumbnail that just opens to a photo (instead of to a little site, which is my eventual aim), I have on average something like 15 photos. Some few churches just one or two, others nearly a hundred. The bottleneck is writing text, which I find very difficult; also, the Gazetteer section of my site has to compete with the American & Military History and the Roman sections of my site, which, especially the latter, are perceived as more useful by more people.
S. Andrea has always been open every time I've been in Spello: my two 3‑month stays in 96 and 97, and my visits in 00 and 04. I hope then that when you get to Spello, it'll be open again; surely the closing must be temporary. I have no information.
Most churches are open, sort of. Daily Mass in the morning, and/or daily Rosary recitations in the evening. The rest of the day they may well be closed, especially if they contain art treasures yet are in a smaller town.
In villages, I do get bolder, since I may never pass that way again; and do try to find the Person With The Key. Sometimes it's the priest, who may live in another place altogether — and since I'm very often on foot, that does me in. More often, however, it's some local inhabitant, or the priest lives near the church; of course, you have to catch them at home. Among those that were opened for me, the great church of
S. Maria at Ponte di Cerreto.
Sometimes you will have the luck of being able to tag along with a
gita, a group of Italian tourists in town from some other place, pilgrims or like pilgrims, conducted by their own priest or a guide, who get the place opened for them. This is how I visited the upper church in the cathedral of Città di Castello (the lower remains open thru the day) for example.
Some churches have posted hours; once they do that they're fair game in my mind, and I hold them to them, and go beard people in their dens until I get in.
The splendid church of S. Francesco in Leonessa is an unforgettable example where I'm glad I did.
Sometimes also they're closed because they're being restored. That usually means in fact that you will be able to get in, rather than the reverse; this is how I visited the church at S. Anatolia di Narco among several examples. Exceptions are usually those where very heavy machinery is involved, or risk of collapse: so far for me, S. Michele in Bevagna, the cloister of Sassovivo (reopened now since my last stay in Umbria),
S. Nicolò in Spoleto.
Weddings and funerals present varying circs. The service itself, like other Masses and like Rosary recitations of course, hardly a time to visit, at best take a very discreet and distant peek. But the preparations for them, either they are glad to show off the church in her best light (my experience at S. Maria extra Moenia in Antrodoco) or on the contrary a photographer will have wrapped up a monopoly on the pictures (my experience once in S. Marco in Rome). On at least one occasion I was mistaken for the official photographer (S. Giovanni a Porta Latina in Rome); I don't go out of my way to disabuse them.
Cemetery churches have a strong tendency to be open round the clock, and extended hours at that, like the church of S. Salvatore in Spoleto. On the other hand not always, like the church of S. Girolamo in Spello.
Finally, every church that remains consecrated, must by canon law be officiated a minimum of once a year. This means that even the most remote rural church, like for example the
Madonna della Spella on Mount Subasio above Spello, will be open at least
once during the year. The trick then becomes finding out when; usually it's the Sunday nearest the titular's feast; often these become occasions for a small town to have a picnic or special event in conjunction with the Mass. If you want to track a few of these down, make a list beforehand of saints' days for the calendar period of your trip, of course; although you can get some surprises: the feast may be kept locally on a different day from that in the universal missal (Norcia for example keeps
two feasts of S. Benedict); or the saint is not the one you thought: St. John might be the Baptist (June) or the Evangelist (December); and not all churches of S. Giuseppe for example honor St. Joseph the husband of Mary, they may be S. Joseph of Leonessa or yet another Joseph.
In Rome, almost all churches open for the Rosary recitation, usually around 6
P.M. My next stay in Umbria, God willing, I'll be in Trevi, where the train schedules are among the most convenient in Umbria for this type of thing, allowing me to daytrip to Rome and return as late as midnite; in turn, letting me visit these "evening churches"; although I will probably learn to say the Rosary in Italian before I leave the States.
As a general rule, the farther I have to walk, the more likely I am to ring bells! For example, the little church (once in fact a powerful abbey) of
S. Silvestro at Collepino di Spello, run by a cloistered order of contemplative nuns: I was still very embarrassed when a pretty young novice literally ran from the convent to the church, to open the building, then ran back — all without saying a word.
One thing I haven't done, in part because I'm so diffident, and in part because I'm not as slow a traveler as I'd like, is drop everything each time and persist until I get in. I think, though, that if you have it in you to do that — the motivation being that you've informed yourself ahead of time of what there is to see in that church (which by the way will add to your credibility and help get you in) — you'll be rewarded 80% of the time.
For my part though, so far, I've usually loped off at the mere sight of a bell, let alone a placard saying to go see la Signora Mariagrazia in her house.