In western movies, there's often the plot; There's a new sheriff in town. For BIAB, the new theme is; There's new math in town.
In older versions of BIAB, the riff feature in BIAB and RealBand would generate seven riffs and after a few regenerations, duplicates might appear. In other words, riffs had a fairly low unique number of generations. As Herb (Guitarhacker) notes above, this is usually enough to get a solid and unique solo. The method he references to generate 3-5 tracks of the same soloist instrument and comping riffs from each is also a very good method to capture a quality performance.
But today's BIAB can generate riffs that blow by the limitations of manually making your own off the charts. Partial regeneration increased riff capability up to 40 and BIAB now has 24 tracks to generate a soloist instrument multiple times on multiple tracks for manual comping.
However, RealTrack Medley Maker, an old feature, has been upgraded from working on the original seven Legacy Tracks to include the 16 Utility Tracks so all 24 tracks can now access this feature. There's an notify message for the Audio Track and DrumsTrack that a RealTrack must be loaded rather than pre-recorded audio or RealDrums. It's a RealTracks feature so Medley Maker applies to all of the 24 Tracks that have a RealTrack assigned.
RealTrack Medley Maker is marketed for two applications, Thickening (using the same instrument multiple times on the same track) or create a Medley of different RealTrack instruments to play simultaneously or consecutively as programed. But for music generation, there are hacks to generate very complex and detailed arrangements that are edited and arranged by BIAB.
The math for using the full compliment of 24 channels to use all of the Medley Maker sub-tracks and have BIAB create a soloist, BIAB would access and generate these sub-track RealTracks 264 times in a single generation that could have volume auto-leveling and panning. The RealTrack Medley Maker has 8 pre-sets that can be set to play a Medley either consequently or simultaneously.
Using multiple Mixer Channels with different variations of RealTrack instruments, applying Partial regeneration and then arranging these tracks into a single, unique stereo or mono soloist Artist Performance Track would be a huge manual undertaking that would require hours to duplicate what a single render in BIAB would produce.