This drives me mad every time I process my monthly invoices, not sure why it's taken me so long to bring it up really! While it's true some default appears when processing expenses and bills via the Documents, it seems to be incomplete in places.
For example, if you select a document that where the vendor got correctly identified, then the category is set too. However more often than not the vendor isn't detected correctly and you have to select it. You then also have to select the category instead of it being dropped in automatically. The screen is probably backward in this respect too actually, it would make more sense to select the Vendor at the top of the screen then have the right category populated.
Additionally, the Paid Through doesn't seem to be populated with the default bank.
Finally, and probably the most annoying really is the VAT rate. Just about everything I process is Standard Rate 20% VAT yet I have to select the rate EVERYWHERE! Interestingly in some cases, the VAT Treatment gets set right, but the rate is always empty.