Former Mercedes man Vowles took over the reins of Williams at the start of this year, having been appointed by owners Dorilton Capital to oversee a complete overhaul of the historic Grove squad.
He found a previously cash-strapped team that had been focused on short-term survival until Dorilton took over its ownership in 2020 and has been severely lagging behind the competition in terms of its infrastructure.
Williams' competitors Alpine had been zeroed in on a five-year or 100-race plan to get back to the front, which ultimately didn't prove ambitious enough for Renault's management and led to team principal Otmar Szafnauer's removal this summer after just 18 months.
But Vowles thinks setting long-term targets like that is "meaningless' because there are too many unknown factors involved in a team's long-term success.
"As I was interviewed to come here, I gave them a very clear view of how long it would take, and it's a long time," Vowles told Autosport in an exclusive interview.
"That hasn't changed. Same with Pat [Fry] when he joined. Pat was very clear to me on 'This will take a while'. I said: 'I know, and the board know as well'.
"So, you have to present sensible things but when you're presenting any more than three years out it's just into the unknown. Definitely at five, 100% at ten.
Source: Autosport