You can easily hit 900 by doing the following;
Day 1: Build and float around 500, you can keep up with that if you play a match here and there through out day.
Day 2: Build Up to 750. 24H Shield.
Day 3: Build up to 850: 8H shield ( or 3 depends on how many health packs you want) Just before breaking shield queue up over 50 points of matches. Should be able to do that w/o getting hit and hit 900.
It's all in when you push, if you do massive climbs at once you are making yourself more visible to everyone and the more you attack the more you will get attacked back. That's why you have to break up the climbs with shields. Sucks spending the HP but if you need the 4*, spending 450Hp on it isn't that bad as you make some of that back during the climb.
So for instance: Iron fist event; If you started Tuesday at 8pm, You build up and float around 550 ( or higher), Wednesday around 12 or 1, use a 24h shield until Thursday, then push between 750-850 and use 8H shield when the event has 3 hours left break shield climb the remaining points ( 3-5 matches tops) hit 900 and shield up for remaining 3 hours if you want rewards, if you don't shield expect to loose 300+ point in 5 mins. Works for me but I hate spending HP on anything other than Roster slots.