According to the GasToken Calculator if you mint gas when gas price is equal to 1 Gwei and free gas when gas price is equal to 50 Gwei (50 x) you'd get an approx. 300% reduction in the cost of gas. However, if the difference between minting time vs freeing time is less than 5x you're looking at a return of only 50%. When analyzing gas price over the past 1000 blocks it doesn't look like the fees ever fell even close to 5x to make the effort vs, reward worthwhile.
So my question is: Is this strategy still effective?