Regarding "fleeces", please look at the scriptural account of Gideon and the "fleece" with God...
Judges 6:36-“And Gideon said unto God, If thou wilt save Israel by mine hand, as thou hast said,  Behold, I will put a fleece of wool in the floor; and if the dew be on the fleece only, and it be dry upon all the earth beside, then shall I know that thou wilt save Israel by mine hand, as thou hast said.  And it was so: for he rose up early on the morrow, and thrust the fleece together, and wringed the dew out of the fleece, a bowl full of water”.
Judges 6:39-“And Gideon said unto God, Let not thine anger be hot against me, and I will speak but this once: let me prove, I pray thee, but this once with the fleece; let it now be dry only upon the fleece, and upon all the ground let there be dew.  And God did so that night: for it was dry upon the fleece only, and there was dew on all the ground”.
That is the Biblical account and the conditions of a "fleece". One must be certain to follow the scriptural parameters when laying out a "fleece".
According to the scriptural account (in setting out a "fleece" for God's confirmation of something), YOU set the conditions for God to fulfill, not the other way around. And the conditions need to be such that they cannot be manipulated by man or able to happen by random chance. In fact, the conditions must be such that there is no possibility of random chance entering into the equation. Why do you think Gideon repeated the “fleece” (reversed it)? So he would know for certain that only the Lord could have confirmed it without human manipulation!
The "fleece" is set out for the Lord's CONFIRMATION of the question you already KNOW. You already know what the "sign" or result is to be expected! It is not up to random chance for the Lord's fulfilling of His confirmation by your "fleece".
If one sets out a "fleece" before God without setting the conditions for God to fulfill, then it is NOT a "fleece" according to scripture. How can God answer a "fleece" if specific conditions are not given? How would one then know what to expect?
If one lays out a "fleece" and is given something that they do not expect to receive, then it is not a "fleece" according to scripture.
In the Biblical account, what do you think Gideon would have thought if he got something that he did not expect? He was expecting "dew" (water) on either the "fleece" or on the ground. What do you think Gideon would have thought if he had gotten MANNA on his fleece instead of "dew"? That surely would be something that he did not expect.
No, in setting out a "fleece" for God's confirmation of something, the person sets the conditions for God to fulfill, otherwise it is no "fleece" at all, but simply random chance that one then has to work hard to make a case for.
Did Gideon say "Lord, I have this fleece here, do something with it and I will then try to discern what I think you are trying to say after the fact"?
No, of course Gideon did not do such a thing.