Thank you for sharing your experiences about the safety zone. It would actually help us too if DPS would share their insights on this so we, together, can do a better team play.
As of the tiles, I do try to put one set outside the boss but the funny thing was I was actually blamed for not putting it beside the boss and may I add that nitpicker was an Archer oh well
My suggestion on Safety Zone is to just stay there for like 3-5seconds only and move to another location.
Like for mages, the only good reason to go near is either put flame ground/fireball , that rain skill of elem and some other aoe since staying near the boss for far too long would be really dangerous and stressful for your friendly cleric if you either got low or rip sliding dead and canāt pinpoint resu you lol.
another tip when you have a priest on a party, dont go behind them since usually they want to maximize mass heal (can only heal infront) and they want to do it when most of you are either near the boss and your tanker or all near each other
From a healers perspective: I do my best at placing heal tilea in beforehand in spots I assume are good for people to walk on when needed. If I have heal off cd and one low hp player gets slow I will ofc try to get to them to heal and if they run too far away I just place the tiles and let them walk back if its safe.
No need to stress ovee that imo. I do my best and if someone avoids my heal tiles in panic then there isnt much for me to do even if the player ends uo dying.
I underatand that people dont wanma rely on safety zone at that point but I always try tocast it in beforehand for those who are meleeing the mobss or mobs. Everyone should learn some awareness and notice me cast it on them while they are still safe, moments before danger. At that point its usually not a wis e decision to run away from a fresh safety zone. Also some people fail and stand on the edge of the circle, missing the circle by an inch and then get knocked to hell.
So far nobody has complained to me if they died but people have complimented me on heals. So healers, just dont stress and do your best. 
Just a small imput from my part.
Instead of running away from the healer, they might be running away from the hoard of mobs chasing the healer 
I already learned in icbts that chasing them is a bad ideaā¦ XD Just put down somewhere the tilesā¦you can try to put it near them but donāt waste too much time with itā¦ If you see them moving away just put it down where you are and hope they will see itā¦(mostly it worked for meā¦they ran there and healed themselves with my tiles)
This.
I sometimes use it near a tank so he can safely aggro while i go heal the rest of the party but the tank completely ignores it.