I have a bizarre classical CD where the last movement of each work is split into two tracks for no discernible reason. The total length of the original movement should be over 9 minutes which makes all the freebie merging programs unusable without paying. (I would pay if I knew the the program worked...
To go specific on my suggestion:
Could there be an option when creating m4b-"audiobooks" to have the possibility to enter an amount of minutes, after which another chapter will be added into the stream? That way, at least I can skip forward and backward...