On a personal note, the Shikker Dovid tries to find moral lessons and ideas in the Torah. The Torah is a guide to leading a moral and ethical life. The bottom line is that Gd wants us to be sensible in our avodat hashem. Although the Torah many times tells us what to do, how often , how much, what percentage- sometimes, it leaves it up to us.
In Parshat Shlach chapter15 verse 21, the Torah tells us “The first of your dough ye shall give to Hashem a gift (Termah). Rashi notes that there is no measurement or required amount (Shiur), however it must be “sufficient for giving”. What does this mean? The Shikker Dovid would like to suggest that although there is no fixed amount, one must be sensible in how much to give. One must give enough that it be useful or practical. The moral lesson here is that, we must use our judgment and apply torah knowledge so we have sensible, moral and proper outcomes in our lives.
We must ensure that we do not warp our decision making under the banner of Torah for illogical, inappropriate or unethical life outcomes.
ShikkerDovid 
excellent insight but I think the Torah teaches more than that. I think that in issues of gifts between man and G-d, the requirement may be put on man, but only an individual knows how much he can give as a gift. G-d does not want the poor to feel inadequate or inferior because he can’t give more, nor the rich to feel superior because he can. By leaving it up to the individual. G-d allows all men to serve Him at the same level, even if their individual sacrifices differ in amount.