Wild Talent 1 (Cosmic: Ignore Prerequisites +50%; Game Time +0%) 
This let's you use any skill once a week without regard to prerequisites. Advantage X is the ability to use this wild talent an unlimited times per day, so we plug in 30 as the cost, add in the modifiers, and solve for the cost of advantage X.
Extrapolating backwards from Limited Uses, 1/2 a use per day is -10% bigger than 1 use per day, and 1/4 a use per day is another -10%, assuming the halving pattern handle holds.
A fixed duration when it is technically an inconvenience is a 0% feature, so stretching uses from once every four days to once every seven days is free. We do not get the -70% break-point for reaching once every 8 days.
Advantage X (Limited Uses, 1/4 Uses per day -60%; Fixed Duration, Once Every seven days instead of every four days +0%)
40% of Advantage X is 30 points, so Advantage X, "Infinite Wild Talent Ignoring Prerequisites" is 75 points.
Everything! at Attribute - 3 = 10 Points
Everything! at Attribute - 2 = 19 Points
Everything! at Attribute - 1 = 38 Points
Everything! at Attribute + 0 = 75 Points
+1 = 75 Points
At that price break it is worth investing up until Attribute for 75 points, and then just buying up attributes.
But always ask the GM's permission first.