Paleontologists agree that organic remains must be buried quickly so they can be preserved long enough to be come fossilized.  However, the term fossilized is not a very precise term.  There are several factors and metamorphic mineral processes which occur to organic remains that result in what is typically called a fossil.  One major factor concerns what kind of organisms are to be fossilized  vertebrate, invertebrates, radiolarians, sponges, plants, pollen, foot prints, etc.  And multiple processes may include permineralization, recrystalization, carbonization, replacement, dissolving, diagenesis, etc.  Talking about fossilization is a complex issue, however quick burial is not questioned.

The major question is, how long does it take for these processes to work on organic reamins in the environment they are found in?  Experimental taphonomy has resulted in an assortment of remains becoming fossilized by various processes in the lab, which of course implies that given the right conditions, vast ages are not an issue.  The metamorphic processes are ongoing until an equilibrium is met between the chemical enviroument of the burial site and the minerals of the organic remains.  Flood catastrophic geologists do not expect that organic remains buried during the flood were completely fossilized within the one year period of the flood, but rather that there has been some 4000 years for the processes to have been working.  Much more work needs to be done on the taphonomy of organic remains.  Yet, how one interprets even those results will depend upon which world view you choose to believe with.