Formula 1 managing director of motorsports Ross Brawn says the new development token system being introduced for 2020 had to be "flexible" owing to its late implementation.
In an attempt to rein in spending, the development of some key elements of the car is to be frozen from the first race of the 2020 season until the end of 2021, with other elements to be frozen from later this year.
However McLaren's plan to switch from Renault to Mercedes power in the middle of the freeze meant that it was inevitable that the team would have to make some changes for 2021.
To allow for that and to give other teams a chance to play a "joker" and change frozen elements of their choice, each team has two tokens that they can deploy with the agreement of the FIA.
McLaren is obliged to use its tokens to pay for the revised engine installation and the changes associated with it.
"When you give somebody five years and tell them this is going to be the situation then you can be fairly specific about what you're going to do," Brawn told Autosport.
"When you tell them with a few weeks' notice, then you've got to be flexible in terms of how you apply it.
"The problem with the freeze was that we had a team that was changing an engine, McLaren.
"You can't ignore that, you can't say that you can't change your engine.
"So we had to find a fair system that was going to accommodate their need to make the change.
"We also recognise that some teams may have a flaw in their car that they shouldn't have to live with for two years.
"The token system allows them just that little bit of scope to put right what they had wrong."
Brawn cited one specific example, with the system F1 has deployed offering a "good compromise" as a result.
"One team said to us that they got the cooling wrong on their car, so they couldn't live with the cooling system for two years.
"So, by just giving them a little bit of leeway I think we've found a good compromise."