My first Levi EX (E3S) clear, week 1
The last Levi EX I uploaded with my group, A few months later
I'd use a turn from a newer tier but my group typically tends to start a couple of weeks after each tier because we are slackers. For Eden's Gate the stars aligned and we actually managed to raid on week 1, we narrowly missed out on a week 1 Titan kill so I'll use Levi instead so that the results aren't being skewed by tome gear etc
Week 1 = 72 Healing GCDs vs 138 DPS GCDs over 10:44
Week x = 45 Healing GCDs vs 143 DPS GCDs over 9:06
By approximation, if the week 1 clear had have died at 9 minutes I'd have used 60 healing GCDs. A difference for sure, but it's not that huge a gap. A 'better' healer than myself would almost certainly optimise their GCDs more by week 8, but they would have also likely been much more efficient than me on their first clear as well.
The TLDR of this is that it's worth looking at some progression footage from pretty much any halfway decent healer. You'll see them nuking pretty much from the second pull onwards because fights tend to be so heavily scripted now. This isn't Extreme Primals or 24 man content, when people mess up and fail mechanics in recent Savage tiers the end result is usually either a damage down, a death or a raid wipe. From the healer's perspective, most situations will cost us a GCD. /shrug.