I've been using the indoor: system to Gazetteer flats in blocks either by outline separated with their corresponding layer/level data or just by entrance nodes were outlines are not clear to me yet.
In basic rendering the view is generally ignored unless you have a renderer that knows how to make a building plan in various possible styles from flat to isometric. big map renderers generally gloss over and ignore these but take the data into a spreadsheet or database and it gives a good postal listing like those that Kelley's used to make. As a data user this is more useful for me than say a number range especially when I try to add office or owner data into the Gazetteer which due to it being in osm allows it to be automatically to custom maps. It also helps navigation when the dwellings aren't sequentially numbered which is actually quite common (from both alterations and odd/even splitting schemes as well as say something that tries to combine floor and unit numbers from to separate ranges. The Gazetteer form just cuts though all of this and makes it straightforward and easy to work with automatically
Josm hasn't been so easy to work with for this needing a layer approach workflow to work and the online editors are very difficult to use with stacked features (think of a 40-story block of flats or halls of residence - the baseplan for most floors in the middle are likely to be very similar with most principle doors and loadbearing walls being in the same horizontal place on each one, with just layer/level/ele/height data to split them up). I have been thinking about writing a new editor to make things easier but I've had so much going on recently that I've surveyed a lot more than I've had time to add to osm lately, especially when I have to work in complex way without online editors, to get the data clear and without unwanted clashes of wrongly joined nodes.
Customised units and dwellings with variant layout features are also easy to handle like this.
-- In general Gazetteering is more useful for data users than large-scale mapmakers though interactive maps could highlight the important sub parts or jump into a building layer mode.
I read that is increasing use of osm to work in 3D on the wiki and the like. Describing where the dentist is on the 4th floor on the northern wing corridor, with these is easy this way.
In general I am adhering to the principles elsewhere expounded in OSM that: -the information provide and stored should not restricted or specially overly tailored to a specific purpose like a certain rendering engine or flight-sim such that it less useful for other users purposes. -If you don't like the rendering, change the render settings not the data per say, -if the render can't understand the difference between things add more differentiating information to OSM and not just remove things or worse deliberately remove detail such as for ways so they "store better on system x because no one renders under [arbitrary] zoom level y"!
It can be tough but it helps to make a general-purpose data set that can be used by so many people in different ways.