It depend on how much information you have.
If you know only first and last numbers (or even only one and direction) - you’d probably use interpolation.
If you know that some address is in some building - put node somewhere in it.
If you know that the whole building have only one address - add address tags on building polygon
If you know where exactly entrance is positioned - adding node on the building polygon with entrance=yes and address info - will be just perfect.
Besides your 1. and 2., there are two other ways of tagging addresses:
A. Add an address property to the building (the way)
B. Create a node at the middle of the building edge, and add the address property to that node
I’m not sure which you mean in 3.
I think B. is better than A. (and certainly better than 1. and 2.). Certainly B. is best on corner buildings (because there is no other way to do two addresses), also anywhere else that there is ambiguity about the address (for example one building between two streets). And in general, I don’t see any downside to B. However, method A. is used in some places already, and I don’t see it as worth changing.
Beside that its better than nothing to do that but it is not a final status, just a temporary one:
A final OSM map should show the housenumbers of each and every building.
So starting with the first and last housenumber is a great step forward but needs guessing to define nodes for every building.
Even if you make a mistake with the housenumber nodes, nobody will throw stones on you.
I personally find it very easy with the right tools (OSMAND on Android) to fix those issues in a survey and make sure the entrance and housenumber is defined 100% correctly.
But it is a very big job.
It took me I think a year to add housenumbers by survey for Netanya.
A personal tip. Before you start tagging housenumbers add all buildings via Bing Satimages.
It is a lot easier to add housenumbers if a building is visible on a map.
Great, so I’ll keep adding house numbers.
A follow-up question, if I may:
Is it OK to fix the address nodes taken from the Tel Aviv Municipality? Is it OK to move, change and delete incorrect address nodes in Tel Aviv?
It is not good. But I think OSM is better with that data as is, than without it.
We could ask them for special permission to make constructive changes. But I think we tried this in the past and they weren’t helpful.
You could maybe argue that each address is an independent piece of data, and if you don’t use (i.e. delete) one piece, you’re not affecting the other pieces. But that argument can be questioned. I’m not sure I want to rely on it.