I was reading a manual for kit that requires you to amplify DNA by PCR before analyzing it in the kit. The manual suggests mixing proofreading and non-proofreading polymerases:
For PCR products >2500 bp in length, use a DNA polymerase blend containing Taq DNA polymerase supplemented with a proofreading DNA polymerase
How would this improve the amplification of long products? It suggests using only a proofreading polymerase for fragments below 2500 bases. Does the addition of a non-proofreading polymerase improve speed? I have TAQ and PFU Ultra, but both instructions say to use an extension time of 1 minute per kb.