Outgoing Williams technical chief Pat Symonds says the development of 2017 Formula 1 cars is "very immature" given the lack of wind tunnel time.
Next year will mark the start of a new era for the sport, with big rule changes introduced with the aim of making the cars five seconds per lap faster and more challenging to drive.
However, the regulations were finalised late and teams did not get the wind tunnel tyres - much wider next year - until February, meaning development time has been reduced significantly compared to previous rule changes of this magnitude.
"I think that the biggest change is that there has been less true development time on it – both time and wind tunnel runs," said Symonds, who steps down at Williams at the end of this year.
"If you go back to 2009, a huge change, but we were talking about it for ages and there were drafts of the rules being pushed around and we were running wind tunnels 24/7 Toyota were running two wind tunnels 24/7. Plenty of time to investigate it.
"The next reasonably large change we had was for 2014, where we had a number of aerodynamic changes plus a lot of new cooling stuff to do and things like that. By that time, we still had a fair amount of time to do it, but we were running at 80 runs a week at that stage.
"This time we got our wind tunnel tyres in late February, so that is when we really started wind tunnel testing. Of course we were doing CFD before that and to be honest, we were doing a little bit of tunnel testing using rear tyres on the front and trying to get some idea of what the basic flow regime was.
"But since February, it has been 65 runs per week and there has been work to do on the 2016 cars.
"So I think that the development is very immature compared to where we have been before, and that is why I am sure it will continue and why people aren't exactly sure of what they like to call targets are, whereas I like to call them expectations," he added.
Despite the changes to the regulations, Symonds is not expecting next year's cars to be radically different when compared to each other.
"I don't. The rules are quite prescriptive. There is an area on the engine cover where we might see a few variations and things," he said.
"There is a bit more of an open area, and a bit more of an open area there but you don't really notice it to be honest. Once again, if you painted them all black you would struggle to notice."
Additional reporting by Jonathan Noble