Well it depends what you mean by that really, it's not really a game you progress through as such, it doesn't have an end really. But you will get access to new planes and tanks at a rate commensurate with the amount of time you play for, it's quick to start with, once you get to tier 4, it slows down a lot and will take much longer, tier 5 (jets) takes, much, much longer.
Paying for a premium account means you will get access to new planes and tanks more quickly simply because you get more experience and more money. I wouldn't say you will notice much difference in the speed you unlock stuff until tier 4 though, then you
will notice it. It doesn't give you a 'fun' advantage though at all, to be honest many of us in the squadron tend to prefer to play lower battle rating, easy to get stuff as it's just more fun, things don't move as fast and you get to feel more like a hero

...and admire your plane and the scenery.
If your idea of fun is flying jets though, it's going to take a while. In which case a premium account may be worth it just to get you towards that goal as quickly as possible. Having said that, you can just focus your playtime a bit to get where you want to go more quickly, I find it fun to fly the aircraft of every nation, but you don't have to and if you don't, you will get new stuff faster.
Having said that, it works differently now, when I unlocked most of the stuff I have the bonus experience system was totally different (much better!) in that each day you could double your XP in the first battle you won for each nation, which encouraged people to fly all nations as they took advantage of this. It's different now. Also if you had a premium account, which I did ..you would get double XP from that and the daily bonus would double that ...so the pressure was on to get a good win for your first each day with each nation ...sometimes this worked out brilliantly and you could land tens of thousands of XP with one win and a lot of cash ...sometimes it was a miserable win and you would waste it.
Best I ever had was one of the special bonus weekends they did where the XP bonus was x5, so premium account = x2 and that was then x 5 due to the bonus. So double it and then times that by 5! ....that's a lot of XP and you really can't get close to that anymore.