I don't do it for a living, never have, but have been building custom rifles for a long time in several styles plus restoration work. I can only answer for my own opinion and here it is. On a new rifle I always glass-bed, on a restoration I use epoxy when gluing broken stocks back together.
Further clarification: if it's visible as a gap-filler then it's unacceptable; on a new bolt rifle I always pillar-bed for several reasons and install stock strengtheners of various sorts but the glass is invisible from the outside. The proper procedure is to first inlet with absolutely no gaps (or in my case as few as possible, G) and then cut out room for the glass & pillars below the wood line.
On a repair I always mix lots of sawdust & wood chips from the original stock into the glass, using the glass to create a matrix with the wood as the primary filler material. I get the matching wood dust and scraps when I drill the holes for the internal wooden or metal dowels that hold the pieces together.
JMOFWIW, plenty of others differ.
Regards, Joe
