To answer the question about the topic, just like many who have mentioned compensating flaps effect for lesser elevator trim. Another use of crow is for descend to produce downward push as well as drag on leveled flight down to negative AoA. I tried using crow for few times on landing to see how's the difference. After finding that it causes to increase my landing speed, I plan to use it for high speed landing proficiency but due to the danger of using it on landing I just reduce the flaps instead to get the same benefits. The last function of the crow on my planes is like a ground spoiler use to add drag, eliminating lift while on full flaps and increase landing gear traction.