Indeed. That's the beauty of using a DLNA mechanism. All the work is done up front and when you add new files, the server automatically scans and adds to its database.
TLDR unless someone else is DLNA curious, but gapless playing works perfectly for my setup (FLAC files)
When a DLNA-aware app 'sees' the server over the network it's just database lookups to present info to the user - much faster than navigating folders and pulling metadata every time. If you use say, FB2K on a phone, it's not DLNA aware (it ought to be, like with the PC version is with a plugin), so it builds its own local database (which works as a cache for tag data), but because all the data is coming over the network and being parsed by a weak phone CPU, it's very slow to do the initial build.
I've experimented with my RAID/NAS (which reads and writes at full LAN bandwidth), and if I wipe the DLNA database and force a rebuild, it's takes two hours to complete! There are a lot of media files on it though. Sure, it's 4 slow HDDs and not SSDs on my NAS, but it's running a decent Intel 4 core CPU. Once built though, the phone app I use for setting up my streamer only takes a second to start populating data on the screen, and as you scroll the display more or less keeps up. You can of course select any of the usual "virtual folders" to display, such as - playlist, genre, band, album or 'by folder', and invidual items show up on the phone with cover art and all the relevant tag data - no larsong, just a a database lookup, and any selection you make to cue to the streamer is more or less instant - and course, once done, the phone is freed up - it's no longer involved in the files that the streamer is playing off the NAS.
Sorry if I'm a bit of a fan of this way if doing things - I've done it this way more or less since it was first possible!