The 22-year-old centre-half initially linked up with the Glovers in September, before agreeing to stay on until December.
He returned to Huish Park on New Year's Day and will now see out the season with Gary Johnson's side.
Duffy admits he could have opted for a change of scenery in January, with parent club Everton eager to get him back out, but the Republic of Ireland U21 international insists he had no hesitation in re-joining a Championship basement battle.
He told the Western Gazette: "It was a good test to stay here. I could have gone to other places but I wanted to stay.
"I thought it would be a test for myself and the lads. I have never been in this situation in my career so I wanted to give it my best shot.
"If we come out of it, hopefully it will be good for my career. It's different to anything I have ever been involved in. Hopefully when I look back at it at the end of my career it will have stood me in good stead.
"We have got some important home games that will see where we are. We have had a rough time with a few tough games and we haven't really got the squad to cover playing them (the likes of Southampton, Derby County and Nottingham Forest) every week.
"But we're going to give it a good go and now we're playing teams around us. We need to win these games, that's what really matters."
Duffy also believes that the tranquillity of life in Somerset has served him well at an important stage of his career.
He added: "It's alright, it's just quiet. It's probably what I needed. I maybe needed to get out of the big city and focus on football.
"Just going to training, going home and often then watching football is good for someone who arrived here aged 21.
"It's good for young people to realise that different side of football, coming from Everton.
"I was speaking to Everton just last week and it was good to hear that they are watching me. They are seeing I am doing well.
"I just need to keep going. The last few games have been a bit mad and we didn't get the results, but Everton saw that and they can see where I can go from here."