The first couple of minutes of break-in on an ABC involves lots of stress due to the tight piston/cylinder fit. We generally use a smaller prop to let the engine rev up and heat up with minimal stress on the bushing surfaces such as the upper and lower conrod bearing, and the crankshaft bearing if it is not a BB engine. The faster these bearings run, the more they are pushed to center and cause minimal wear.
Some engines that are converted can handle these pressures, but additional pressures caused by diesel ignition can take it to (or beyond) the breaking point.
I guess part of the answer is that it depends on the engine. Purpose-built diesels are designed to take the stress.
You have a choice, follow the manufacturers instructions or try it your way. Both will probably work. Keep in mind that parts are designed for more stress in a high-performance engine than a sport engine.

George