Yamaha MotoGP riders Valentino Rossi and Maverick Vinales both reverted to 2016 chassis for Sunday's Valencia season finale.
After Rossi and Vinales qualified only seventh and 13th respectively, the works Yamaha squad made a last-minute decision to switch to the same year-old bike specification Tech3 satellite rider Johann Zarco had used to take second on the grid.
The only set-up time the works riders had with the chassis prior to the race was in the 20-minute morning warm-up session.
Rossi said this meant the result would have been "more or less" the same no matter which bike was used, because "it's quite difficult to try to improve a lot in one day" but felt it was worthwhile trying the 2016 chassis in the race rather than waiting for this week's two-day test.
"Sometimes in a race you understand more than 10 days of testing," said Rossi.
"Unfortunately it's not [the thing] you put on and everything becomes better.
"But I think we understand something interesting. This bike is easier to ride, you feel better in general."
The Valencia change marked the fourth different frame the two beleaguered factory riders have used across a frustrating 2017 season.
Rossi finished the race fifth, dropping him to the same place in the riders' standings behind race winner Dani Pedrosa, while Vinales could no better than 12th.
A double DNF for Ducati meant Yamaha did at least get the consolation of being runner-up in the manufacturers' standings behind Honda, but 2017 became the first time in a decade that Yamaha did not have a rider in the top two in the championship.
Vinales' already-limited set-up time on the old bike was curtailed by an early crash in warm-up, although he said he was "feeling great" in the two laps he managed prior to that.
"Already on the first lap I did a low 1m32s, second lap I was already one second faster," said Vinales.
"I was feeling great, maybe I pushed too much and too early, because I was feeling good.
"Anyway, in the race we had some issues with the rear tyre. The feeling I had was that the tyre was not working well, a lot of vibration at the end of the race. I didn't want to risk more than necessary.
"I felt really great in the morning with the 2016 bike, even only for two laps, I felt better than all the weekend."