No - 50 minutes a junior spends trying to solve stuff on his own is 50 minutes invested in being more independent I consider that an overall gain.
I would take a junior that comes late with his tasks but mostly works independently over a guy that's asking the rest of the team for every setback so he can deliver the stuff he promised any day of the week. Juniors are almost always a net negative for the team - the ones who know how to reduce that are a huge benefit.
