Does one need more or less paperwork while applying?

Last week i inquired thru a lot of immigration agency for tier1 visa. An agency told me that there is no need to submit more and unnecessary documents as BHC dos not have time to go thru all the papers For eg All previous work exp letters, 3 yrs income tax, property documents etc. whereas two other agencies told that they prefer submitting more papers to make the case strong. According to one solicitor here in mumbai he told that once you apply for an visa and if it is rejected you cant submit fresh papers for evidence or to make your case strong you need to argue on the same papers which were submited when u go for an appeal. Is this true? Pls help.