Guild Wars 2

Im finding 650~ is a sweet spot. I tried 1150 with bloodlust bonus but found no benefit

There becomes a point where having too much healing power will affect how much pressure you can put on the enemy. An enemy that isnt pressured is an enemy that is attacking.

If you don’t want to waste more stat points in healing power than neccessary (regarding the coefficient on your skills and traits), you should aim for a value which is divisible by 200 without remainder.
Cleansing Wave and Healing Ripple scale by 1.0, Soothing Mist by 1/20, Cone of Cold by 8/25. Regeneration scales by 1/8 of your healing power. LCM of the fractions is 200.

Any value with a reminder means, you wasted some points (due to rounding down) which you could’ve spend somewhere else.

Personally, if I run around in my support build, I aim for ~800, which gives a clean 230 hp via Regeneration, 120 hp via Soothing Mist, and around 2.1k hp via Cleansing Wave (2x if you also use Arcane Evasion) and Healing Ripple. Cone of Cold gives ~1k and Ether Renewal heals for up to almost 6k (Signet of Restoration would get me 282 HP per spell).

If I’m on a killing spree, I like to aim for 600 healing power, but depending on my gear, sometimes I only run 400 and can do just as fine against most enemies, whereas sometimes an additional 20 HP per second are the thing that keeps you alive / allows you to keep pressure on an enemy.

I think you are right.

600 is a nice good all-rounder to have