Oh, I always get all vexed about school holidays!
It isn't so much the cumulative time (though I confess I do resent INSET days!), it's more the weird spread. This is becoming more of a thing now that 'summer' seems to be getting earlier and earlier. I mean, last year, here in Hants, it was March, the previous year it was in April. Come August it's pretty much wall to wall rain these days, isn't it? So I'd rather the DC had 2 weeks off in June, 4 in 'August' and 2 in mid October to at least increase the slight chance we might get some reasonable weather. I also think 2 weeks is the ideal holiday time. A week away and you're only just hitting your holiday stride when it's time to pack up; weeks on end and, rather like the effect if Christmas came every day, the appreciation of that 'down time' is lost in familiarity. My DSs are actually quite glad to get back into school routine come September, actually!
I also don't really think DC need 6 weeks off in one hit. I know that yes, they're only DC once, we shouldn't wish their childhoods away and so forth but 6 or even 9 weeks doesn't really give an older DC any concept of the reality of what life's like when you get 4 weeks all up as an adult! It has always been my 'observation' that these looong summer hols are most favoured by non-working mums who suddenly don't have to do anything against the clock each morning as opposed to getting DC off to school. You will also find -ahem- that many staunch supporters tend to cite southern Europe or Ireland as to how 'it didn't do me/my DC any harm' - all PIIGS countries, one notes!
I can only speak for myself, here, when I say that for my DSs, they (and their teachers agreed with me!) tended to find it was October half term before the DC had got back to where they'd left off in July, but I am aware that this view is only narrowly held: most MNetters DC are gifted therefore hit the ground running after a summer of either 'Lashings of Ginger Beer, out from dawn til dusk' or the Latin summer school in Milan they begged to attend for 4 weeks. Or away at gran and grandpa's summer house in Spain for a month. And so forth.
So everyone has their reasons to love or hate the existing arrangement- but do bear in mind it's an ancient throw-back not predicated on modern evidenced-based research! Like when Easter is so late the DC have been in school for months on end without a break. Try that with a 4 year old. And the next term is 8 weeks long in total!