As stated by others it is about what the total gain that loan is providing. It is fine running one house slightly negative if you can purchase others that are producing full rent with the mortgage you gained from the first. If taking the full LTV out versus the lesser (i.e. initial investment) is going to put you in a better position such as allowing you to buy 2 houses instead of 1 then it may be the better option.
I have not been anywhere close the extreme your describing but usually my all in costs are 25-40% LTV and my bank is willing to give me 80%. I am able to gain instant business capital (i.e. usually $10k to 20k per deal) while still cashflowing $100-$300 on 15 year loan terms.
Again no where near what you are implying but here was my last deal:
Purchase + Rehab: $24,000
Appraisal: $70,000
Loan: $50,000
Debt: $410/month on 15 year note
Rent: $875/month
Gross Cashflow (Rent - PITI): $370
Net Cashflow (Rent-PITI-Vac/CapEx): $195
I gained $26,000 in business capital and if I can somehow manage to pull similar pricing I have essentially just turned 1 house into 3. As well I am still managing about $150-$200/month cashflow on a 15 year loan which is atypical to what most are doing at the moment.
I have (2) more very similar in the works at the moment. Right now my biggest fear is how much to leverage as all CORF seem to require personal guarantors.