Next week the Reds head to Sweden to take on Ajax in the Europa League final looking to win the only major trophy to have eluded them in their success-laden history.
Balancing the desire to win with resting players has been difficult and Mourinho said it would have been worse it not for Oliver's decision to red card Ander Herrera sending off in the 1-0 FA Cup quarter-final defeat at Chelsea in March.
Mourinho has prioritised European success for several weeks now and, like at Spurs, plans to rotate his squad at Southampton on Wednesday, then again in Sunday's Premier League finale at home to Crystal Palace.
"The accumulation of the games, I never had that," said Mourinho.
"You know that in all of my career I was never (knocked) out of European competitions in the group phases and in the last 16 I was out only once.
"So I reached the semi-finals 10 times, I go always until the end of the competitions. In the League Cup I normally go far. In the domestic competitions cups, I won in Spain, in Italy, in Portugal so I normally have a lot of matches. But like this I never have, I never have.
Manchester United's Marcos Rojo and teammates remonstrate with referee Michael Oliver after Ander Herrera was shown a red card
Image credit: Reuters
This situation of you play a final and the game that you should play that day is going to be postponed until the last week, for the last week! This is crazy.
And I repeat the same - thank you Michael Oliver because we were out in the FA Cup, because if we go to the FA Cup semi-finals it would be a total disaster. I don't know when we would be playing that game.
"I never, ever have had a situation like this and on top of that the accumulation of big injuries, not small, not the injuries that you say 'okay, hamstring, two weeks'.
"No. It's surgery, boom, boom. It's surgery - one knee, another knee. Another foot. Just big surgeries.
"So fewer players and fewer players and fewer players. It's very difficult, really very difficult. But we are there and we go to the final."
Mourinho says he is having to do "a la carte" preparation for his players, juggling rest, preparation and matches.
Jose Mourinho Manager of Manchester United speaks with Referee Michael Oliver at the end of The Emirates FA Cup Quarter-Final match between Chelsea and Manchester United at Stamford Bridge on March 13, 2017 in London.
Image credit: Eurosport
"Sometimes you need a day off and they don't know what a day off is," he said.
"So this is a period in one week when I have to give one day off and now I give a day off to (Antonio) Valencia. It has to be.
"And against Crystal Palace two or three more and against Southampton two or three more and that's to try to arrive in the final in the best possible conditions."
Mourinho wants to win both league matches but is not getting strung up on the outcome, given victory against Ajax is the overriding goal.
Europa League glory also offers qualification for the Champions League - the only way they can return to the continent's top table after Sunday's 2-1 loss at Tottenham officially put a top-four finish out of reach.
"What I want for the players is a good attitude, is a positive attitude, a positive approach, is team spirit, is understanding that some guys they have to sacrifice themselves for the good of others," the United boss said of the Saints and Palace matches.
Belgian midfielder Marouane Fellaini celebrates with Manchester United's English midfielder Jesse Lingard (L) after scoring the opening goal of the UEFA Europa League semi-final, second-leg football match between Manchester United and Celta Vigo at Old Tr
Image credit: Getty Images
"(Daley) Blind played today after 90 minutes on Thursday. The next one, of course, (Marouane) Fellaini has to play the next one.
Team spirit, empathy and the fantastic attitude that everybody has is not one more victory, one more point, one more defeat that is going to change something.
"A final is a final and we have to go to the final with everything like Ajax does because they have finished the season and they do not have any more football to play until the final."
Zlatan Ibrahimovic, Marcos Rojo, Luke Shaw, Ashley Young and Tim Fosu-Mensah miss both of United's remaining Premier League matches through injury, while Mourinho is expecting to be without Paul Pogba at Southampton after the midfielder's father died on Friday.
"I don't think (he will be available)," Mourinho said. "I think that his dad's funeral has to be between Tuesday and Wednesday in France.
"I don't think that Paul has the conditions to play. We have left him completely free to be back when he thinks he's ready."