every situation is different, and its hard to set a hard-and-fast rule. in high d1, i won't take project players under 70 or so work ethic. it just depends where you are. fundamentally, the question is, by the time i need this guy, will he be good enough? with most low work ethic players (sub 20 to sub 30), the answer is no, but there are plenty of guys who start with good ratings where you need them, and even if they won't ever come close to maxing, they will get where you need them in the areas you need.
offseason improvement from work ethic is huge. guys who are like 40-50 and under basically grow very little in the off season. for project players, this is often unacceptable. the really high potential guys, regardless of their caps, usually won't come close to capping out until they get up in the high ranges (70+). i think people often ignore work ethic if a guy only has a medium amount of growth, but the reality is, even guys without much growth, won't really cap out without quality work ethic. those last 5 points in a category come so slowly in the regular season, its the offseason that usually gets you there, and that takes high work ethic. not really going anywhere with this, just a general comment.