Since you have looked at the debt related fields closely, I have a question for you. How does DTI relate to the various debt balance fields? I know this may be a little hard to figure, because the payments on various debts depend on their terms (rate, maturity, etc). I have no idea what things are counted in DTI, and I've never tried to figure it out.
In the past, LC's DTI has not included mortgages nor the payment amount of the requested loan. It has been based on borrowers' self-reported income, which may or may not have been verified. So if the borrower is honest and accurate, the DTI relevant to revolving balance and installment payments should be accurate after the required minimum payments due according to the credit report are added up. I asked once about what is included and received a good answer that I no longer seem to have. Darn. You have a good point about maturity. As time goes on, old debts may drop off and new ones be added, so the DTI only helps at the beginning.
A recent loan seemed to have a high income for a "server", so I wondered if tips were included. LC says "under the table" income doesn't count. But if tips are reported to the IRS, it should count, so I took it at face value. For whatever reason, the loan was just removed.