Much of what was learned in the sunny Montreal Friday practices may well turn out to be of marginal value - given that the forecasts are saying 50-60 per cent chance of rain on race day.
But either way, this looks set to be a fascinating contest. We could have either a dry race with three, possibly four, competitive teams at a track where overtaking should be rife, especially with the first double DRS activation zone. Alternatively we could be about to step into the unknown of a wet race on Pirellis.
Last year's crazy tyre-dominated race here was cited as a loose template for Pirelli for all the races when conceiving the 2011 tyre. Five of the first six races have certainly met that brief.
Ironically however, a dry race here on Sunday seems unlikely to recreate the spectacular tyre degradation that brought last year's event alive. A great dry race looks in prospect here for reasons other than tyre degradation; both the super soft option tyre and the soft prime proved capable on Friday of long duration runs. There will be no repeat of last year's Bridgestone option tyre degrading to uselessness within five to six laps.
"Last year it was all about the massive graining we got with the Bridgestone here," said Jenson Button, "but with this tyre we simply don't get graining. What we get is wear and degradation of performance, but graining is not an issue."
With up to 26 laps on the prime and 15 on the option on Friday, two-stop strategies look perfectly feasible for the 70-lap race. The soft appears to be the faster race tyre and although two red flags in quick succession near the end of FP2 spoiled the hot-lap evaluation of the super soft, it would appear to be substantially faster in qualifying.
Pastor Maldonado fitted it to his Williams earlier in the session and improved on his prime tyre time by 1.5s. A two-stop strategy of option/prime/prime is suggested as the standard default for those getting through to Q3. But obviously this tends to get skewed on race day as teams attempt to leapfrog positions by using the undercut effect of pitting early to get track position. "Anything between two and four stops," said Fernando Alonso. "They all look feasible, it just depends on where you are and what are your circumstances."
Overtaking should be what brings this race alive. Even before the advent of DRS, the Circuit Gilles Villeneuve has always lent itself to cars passing and re-passing. But for that to have maximum impact of course it requires cars that are fully competitive. What are the chances of Red Bull not being dominant? Surely pretty good, given not only how quick the McLaren has been on race day recently - it was arguably quicker at both Barcelona and Monaco - but how this track of long straights and slow corners is not aerodynamically demanding. The RB7's downforce advantage will not count for as much, and both McLaren and Ferrari - and possibly Mercedes too - look potentially very quick here.
Too much should not be read into the list of FP2 times, with Alonso's Ferrari heading the pack from Sebastian Vettel's Red Bull, Felipe Massa's Ferrari and the two McLarens of Lewis Hamilton and Jenson Button. These times were set in varying circumstances, the picture muddied by those two red flags.
Alonso's time was set on super softs on his last run, Vettel's, Massa's and the McLarens' all on the slower soft tyre. Mark Webber, back in seventh, was running significantly higher fuel loads than Vettel so cannot be compared either. The Mercedes of Nico Rosberg and Michael Schumacher concentrated on heavily-fuelled long runs in the afternoon, but in FP1 showed a more representative turn of speed that would have put a Merc among the top three in the afternoon had it been repeated.
"I'd be seriously worried about the Mercs actually," said Button. "They get 20km/h from their DRS compared to about 12 for most of us. Around here that's going to be a big advantage."
Button is also very aware of just how phenomenal his team-mate is around here. "I got within 0.4s of Lewis here last year - and that's about the closest anyone's ever got. He's fantastically quick around this place."
Given all this, perhaps Button might prefer the wet race the forecasts are predicting. Pirelli is ready: "The challenge is more for the teams," said Pirelli's Paul Hembery. "The likelihood if it rains is that the temperature will still be quite high, so as it stops you are likely to get an Asian-type of situation where it's evaporating very quickly and the teams will need to be really on the ball to monitor how quickly they can get from wets to inters or inters to dries or even wets straight to dries. I think it's going to be a fantastic race, wet or dry."