The Red Devils have enjoyed a full week without a fixture, following the 2-1 win over Leicester in the FA Cup on 7 February, which has given them time to work on tactical problems and injury recoveries.
"We had some issues at the end of the week with players," Amorim told the club's media. "And that was the hardest part of the week.
"It was a good week to improve on physical aspects but also tactical aspects."
Dorgu signed for United from French club Lecce on 2 February, and has had to find his feet quickly to help his new team bounce back from a disastrous run of results.
The 20-year-old left-back made his debut in the FA Cup win over the Foxes, coming on at half-time, and Amorim believes the Denmark international quickly adapting to his new surroundings.
On Dorgu, he added: "We work with him and he is understanding better the way we want to play.
"He has some habits from the last club [Lecce]. In the first moments, he has had to change things, but it has been a good week."
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