In my case in our village, I live on a private lane and I am the only one with a UG feed (underground) and in our manhole I have my own 4 way CBT, and was told they only light up 2 ports, I ask why, one working and one spare if the other goes down.
Our fibre goes through many nodes (joints) on the way to an exchange 12 miles away and not our local one 3 miles away.
It has nothing to do with any cabinets.

Our Local farms and near by properties may have there own 4 way CBT or one larger one (that's worked out in the area survey.)
They have various lengths of pre-connectorised fbre cable up to 350 metre's that go to the properties from the CBT.

There are No maps for the public to access.

See Link

In reply to a post by Pheasant:

Also how many PONs do they typically run to a splitter node? There must be at least a choice of primary and secondary PON? (appreciate this could be commercially confidential, so I'm expecting a "no comment" 😂)

In Urban areas they usually put 2 or 4 separate splitters in to a single enclosure.
So up to 4 PONs per Splitter Node.

Confusingly, OpenReach actually label this as a single PON, so up to 120 properties per "OpenReach PON".
Technically it's 4 individual GPON PONs, fed by 4 fibres.

Although it's a 32:1 split they try keep 2 spare per Splitter.

In my new build that was retro fitted with FTTP last year they did 2 splitters per enclosure, so up to 60 properties per enclosure for the whole development.

Thank you

Thanks John. Very insightful as usual.