I find it difficult to believe that you only lose 1 GCD per minute. There wasn’t any evidence of these test results provided by the person who put them forward, so hence my skepticism. As well as just with how macros in this game work in general.
Last I checked, you couldn’t program them to function with <wait.2.5> intervals, meaning you’re either having to do <wait.2> or <wait.3>; which will result in GCD clipping and delay. Each GCD clipped/delayed adds up in the amount of GCDs you lose.
If you do a base <wait.3>, then after 5 GCDs at a 2.5s recast, you’ve already lost 1 GCD. And that’s only after 15 seconds by the macro’s standard, AND at base GCD. So not accounting for any sort of spell speed you may have on your gear that causes your GCD to be even lower. Weaving oGCDs will clip and delay your next Dosis cast even more, since macros won’t queue. Assuming you have no oGCDs to weave, over the course of a minute at 2.5 GCD, you would get 24 Dosis III casts. If you are using the <wait.3> macro, then you only get 20, resulting in 4 lost Dosis III casts. After two minutes, 8 lost casts. Three minutes, 12 lost casts. It adds up; and it will only get worse any time you need to weave in an Addersgall ability or Lucid Dreaming, which you should be doing for mana upkeep.
Just because this isn’t Savage/Ultimate tier play doesn’t mean you should enable bad playstyles.
You are likely struggling to retrain yourself to not use macros because you’ve grown complacent using them. They’ve become a crutch you have started to rely on, and you don’t know how to function without them. There will always be learning curves when you start trying something new—such as not using them—but if you keep going back to your old style of playing, then you will never learn the new style.
I never said anything required perfection to clear. That doesn’t change my stance, though. If I get a sprout healer that asks me for advice, I’m not going to hand them a crutch to use. I’m going to advise that they learn how to toggle between tank, party members, and bosses/mobs versus using <tt> macros. There are some abilities I would recommend a <tt> macro for, such as perhaps Krasis and Exaltation; but I would never recommend macroing their GCD healing abilities to them.
I’m not a 99th percentile healer either, by the way. You don’t have to be to not use macros.