Show Icon Preview on Desktop inconsistant?

[Super Ted]

WHen I use the "show icon preview" option on my desktop it rarely works for newly placed images or files. It shows a default icon for that file type until i open view options, uncheck "Show Icon Preview" and then REcheck the box.

Is there a way to speed up how often my desktop refreshes so my icon preview always works?

 

[Super Ted]

vs

 

[big_malk]

The same the often happens with my downloads stack, but not all the time.
It's quite annoying when all of a sudden I don't get previews of new files