should NEVER be applied dogmatically. They woud all spin in their graves if you tried to make a dogma out of their works. That doesn't mean you ignore them however. The overall THEORY of Marxism (a materialist reading of historical processes) is correct enough and flexible enough to encompass all situations. And Lenin and Trotsky both led a successful revolution based on Marxist theory, so you can't discount their insights into revolutionary processes either. But you can't apply their insights dogmatically in every situation. What's more, they wouldn't have either.
As an specific example, since I'm a Trotskyist, I believe in the working class having the ultimate power to make a socialist revolution and to make it permanent. Which is why I'm not a big fan of Che Guevera as a revolutionary. He was something of a Trotskyist in that he saw a United Socialist States of Latin America during a time when all Communists were required to support the USSR even over and above their national interests, BUT he tried to make his revolutions based on guerilla warfare based on the rural peasantry rather than the working class. It worked in Cuba because the character of that revolution was nationalistic from the beginning and not socialist. It only BECAME socialist (or Stalinist) after Castro took power. Imposed from above. A Trot would not have tried to apply Castro's solution for Cuba to Bolivia. But a Trotskyist WOULD have tried to apply the OVERALL theory of the working class making the revolution with the SUPPORT and help of the rural peasantry to ANY country. IOW, the impulse for socialist revolution must come from the working class. A populist revolution might come from the peasantry and a populist revolution might be turned into a socialist revolution (theory of Permanent Revolution), but it wouldn't BE a socialist revolution until the working class became involved in a leading role.
This should be an example of how Marx, et. al. (and especially Trotsky of course), SHOULD be applied, IMO. The general theory is that no socialist revolution can be permanent unless the impulse comes from the bottom up within the working class itself. But the SPECIFICS as to HOW that impulse is stoked and applied would change from situation to situation and country to country.