He is partly wrong and partly right. Let me tell how:
By his method of pan opening, only slightly more oil will come out... My guess .... Slightly less than 4lit. The total capacity is 7.5 lit ... Mentioned in your car manual. By this way you'd get only able to change 53% or less.
The three time method will allow you to change about 72%.
Please note the method that I stated is not my personal suggestion, in fact it's Toyota suggested.
Very important is to finally ensure the fluid level by Temperature Detection Mode.
Why don't you go to Toyota 3S and insist for this right procedure?