A persistent groin injury has hampered Palmer's impact for months.
The 23-year-old was used only as a second-half substitute as Chelsea bowed out of the EFL Cup with a semi-final defeat to Arsenal on Tuesday.
Palmer had played the full 90 minutes just three days previously as Chelsea came from 2-0 down to beat West Ham 3-2.
One of the issues that led to Enzo Maresca's departure as Blues boss in January was a disagreement over his management of the squad with senior figures at the club insisting the medical department had a greater say on selection.
"We have the best medical team in the world and the best sports science team in the world and we want to make sure the players can play to the level needed to help us win," said Rosenior.
"There isn't a time frame that he's going to be perfect in one month or two or three - it's just game by game."
Trailing 3-2 from the first leg of their EFL Cup semi-final, Rosenior's cautious approach for the second leg drew criticism for not being daring enough.
Chelsea dominated the ball for long spells at the Emirates but rarely threatened before Kai Havertz scored the only goal of the night deep into stoppage time.
However, he defended his gameplan and the performance as Chelsea kept the tie alive for 97 minutes against the Premier League leaders.
"What people say outside the club makes no difference to my decision-making," added Rosenior.
"In hindsight, we didn't go through so there are always things you can do differently, but that was a very, very solid performance against a team very good at home."
