Martinez brought in Romelu Lukaku, Gerard Deulofeu and Gareth Barry on season-long loan deals last year, and that trio have been influential in guiding the club to the brink of Champions League football.
Following a run of six straight Premier League wins, Everton sit fifth in the table - a point behind fourth-placed Arsenal having played a game fewer than the London club.
|6/4||Everton are 6/4 with Bet365 to finish in the top four|
And ahead of his side's trip to Sunderland on Saturday, Martinez waxed lyrical about the loan system, claiming that any criticism of its use is "ridiculous".
"The loan system is something that has to be part of the game," he said. "Young players need an opportunity to develop, but it is difficult to find a loan relationship that works.
"People will go against it, it has its pros and cons. From our point of view the loan system is vital but to criticise it is ridiculous. It would be like criticising us for giving youngsters opportunities.
"Sometimes young players get attracted to the glamour of a young club but you need to be realistic.
"It can be very, very difficult for a young player to have an opportunity in the first team.
"You could find many examples of players who have been treated unfairly just because they are not part of the long-term future of the club."
Martinez also said that captain Phil Jagielka was nearing a return after six weeks out with a hamstring injury.
"We want to make sure that he's 100 per cent to play 90 minutes so we've organised a behind-closed-doors friendly," the Spaniard added.
"He's reacting well to treatment, we need to make sure we give him every opportunity to be fully fit.
"We're hoping that he will be available over the next 10 days but it will depend on the exercise behind closed doors."