I rarely build monestaries....however my view is that if I never build them then it shows I`m not understanding something
So maybe you better players can explain the benifits to me?
I tend not to found religions and am happy to wait till org. rel. to spread what I may have recieved
it seems alot of hammers for a temporary 10% science boost
I can see that if the AP is of the same religion or maybe you have the Uni of Sangkor they would be handy
What am I missing?
Exploiting the power of religion takes some effort, but the benefits can be pretty great. The boost is 10% per monestary, so if you have three of them in a high-science city, that is +30%. Should you be able to get all seven, that's an amazing +70%. Sure, it wears off, but while it lasts it gives you a substantial science lead.
After they expire, you can't build more. Unless you want to be locked to Organized Religion, or are Spiritual so that anarchy isn't an issue, you must have monestaries in order to spread religion (and thus temple-happiness and culture). While Organized Religion is good, the others offer benefits worth taking, and I don't like having my options tied.
The culture boost is quite nice. They come early enough so that they are doubled in the late game, a nice bonus if you are going to try for a culture victory. The culture doesn't go away when they expire.
The AP religion bonus is nice, and of course a bonus, as is Sankore. The AP bonus makes a monestary pretty effective.
Founding religions is a way to make a load of money. Religion, shrine, spread like mad, and use your religion to win friends, and if possible through the AP, control people. Monestaries just play into this, though their true power comes from having them all (just like cathedrals, whose cultural and happiness power is amazing when stacked seven high).
As for never build, I say "never say never." There are things I rarely build, but some games call out for them. Circumstances and strategy define what is necessary.
I rarely build musketmen, ironclads, and explorers, but each has uses. A slower-speed game gives more reason to pick intermediate units with a limited lifespan. Explorers shine on the Terra map, with its late-game unexplored territory, and remain useful as defend-only medics.
I don't like Nuclear Plants because the meltdown risk is too great, and Coal plus Recycling or Hydro are usually easy to get. But with few rivers or no coal, they can be the only option to get power for production. Keep a lot of workers on-hand just in case.