Let's assume that given your daily experience with different liquids and knowing that some are "thicker" than others you state this theory:"A body which falls into a liquid which is twice as "thick" as another one, takes twice the time to cover the same distance". You have deduced -theoretically?- that because they are twice as "thick" some liquids brake twice as much as others. Do you agree with this theory? The only way to prove if it is right is to test it experimentally. Use the visual on this page.
Try to state other theories about bodies of different mass or shape falling into liquids. Write down the theory and try it out experimenting with this visual.