the traditional rule of thumb is that there is only one position where you MUST take one kid a year, and it better be the best kid you can find, and that's QB.
it used to be, that RB was a position that you alternated taking one and two a cycle, with teams that ran offenses where the TB position had 30 carries a game, two being the target more years than not.
now, in the modern game, the baseline is one TB per cycle, as offenses are less geared to the 30 carry model, it's one TB a cycle being the norm. (even the NFL has evolved to deemphasize the TB position, which is why you see the draft trends play out as they have the past 5+ years).
if there is an injury situation, or depth problem due to some other attrition, then you would take two. but today's typical roster will have min 4, but no more than 5. Travel squad will have no more than 3 TB's and it's not unheard of to have two, based on that week's game plan.
again, this are targets for roster management, not rules set in stone. but they have served well, and most coaches accept the guidelines, making adjustments as circumstances dictate.
as we knew travis was leaving early, we took two last year (5 star Lingard, and 4 star Cam). that's a load.
this year, as we know burns still is struggling with injury, we added Martin through the portal, and will have 5 star Chaney next spring.
that's two 5 stars and two 4 stars in the last two cycles, and it's not clear that any of them are starting next season ahead of DJ Dallas who is a really good football player. I call that stacking chips.
do we need to add one in addition to chaney? based on the above, no. but if we do, they better be a dead drop stud because i'd much rather see the scholly go to an OT, than a kid who will sit 4th on the depth chart for 3 years.