Recent speculation suggested next season could incorporate 22 races, only for India to fall by the wayside for one season as F1 supremo Ecclestone looks to reshuffle events for 2015.
At present there is a minor doubt over Russia, although a dispute between the Russian Automobile Federation and promoters JSC Omega is close to being resolved.
Bigger question marks hang over another potential debutant in New Jersey, whilst the race in Korea always appears in jeopardy given its location and poor attendances.
With Austria due to return next July after a 13-year absence, it is likely when the provisional calendar is announced towards the end of next month there will again be 20 races, potentially 21.
Whatever the number, Whitmarsh can appreciate Ecclestone's desire to continually seek new events.
"In fairness to Bernie he has been pretty good at finding new venues," said Whitmarsh.
"In this (financial) climate there are always locations in doubt, so therefore having some back-ups is not a bad idea.
"I don't know if the calendar will grow to 22. It would certainly be incredibly tough on the teams, but that's the business we're in.
"We all thought a few years ago that going beyond 16 would be tough, and a lot more of them are outside Europe now.
"Myself and the drivers have a comparatively easy time compared to the guys who build the cars and do all the back-to-back races, it's very hard.
"But we have to support Bernie. Formula One needs some of these new venues - Russia is an interesting market.
"But with questions marks over some of the venues we have, you have to keep the conveyor belt rolling, and he's been pretty good at orchestrating it so far.
"Personally I don't think there will be more than 20 next year, but it is for others to speculate on which races will be on the calendar."
Sauber team boss Monisha Kaltenborn feels F1 is currently at its limit with 20 races, both in terms of manpower and the appeal of the sport as a whole.
Kaltenborn said: "We have to be careful what kind of overall impact this has because we know at the moment 20 races are already quite challenging for the personnel.
"If you increase the number of races you have to keep in mind what implications does it have on the people to start with. Do you need more people?
"You have to also consider the market. If you saturate it too much with races it might not be good for the overall product.
"These are issues we have to look at clearly and then decide if it's good or not good. From the current structures we have, going above 20 would be too many."