Master (sometimes plural you see it frequently in canon with Bonded Master Mercantylers in the larger urban areas and other guilds like GoAL (Chantries so probably the most common IMO), Heralds (Colleges), Masons, Miners and the larger Clothier Clans or Organizations), other guild workers and laborers (includes paid (temporary and permanent (Masons and Miners spring to mind and Mercantylers with Men at Arms or Mercenaries)) part of the nature of the Guild structure is a single Master or Masters cannot start churning out bunches of Journeymen because he wants to completely abuse the concept of free labor.
Plus family children up to age 14 or so and possibly older who have not been apprenticed and are not necessarily paid except in room and board with a possible allowance.
There is a reason characters receive those starting family skills
Guild membership is a privilege not a guarantee. Clan politics even the eldest child and presumed heir might be passed over in favor of a favorite or more popular or promising child. IMO in most P-Harns families will have more than one child apprenticed in the family trade or another if possible and not resource prohibitive. The common guild and other free children are always free to leave at age 13+ in most of the world even if it turns out to be the worst mistake of their life like FFF Odell of Risen