Apparent contradiction in rules about writing that I learnt throughout my education

Question

I noticed that there are a few inconsistencies in what I was taught throughout my English education, and I hope to clarify them. I think the nature of the question is somewhere between "grammar" and "English pedagogy."

*I apologize ahead of time if this question is not appropriate on Writing stackexchange. I am new to the community. Please feel free to migrate the question to other communities, as appropriate.

**For context, I am a student in the natural sciences who had most of my education in the U.S., but am from a non-English speaking country.

Here are a few examples of such contradictions:

I.) In high school, I was taught not to write "run-on sentences," but in college, I was not discouraged from doing so. In fact, many authors I read seemed to write run-on sentences in a lot of places.

II.) In high school, I was told not to use passive voice in my writing. (The reason I was given was that it unnecessarily makes sentences longer.) Again, I was not discouraged from doing this in college.

A more extreme example:

III.) In elementary school, I was taught that an essay should consist of five paragraphs. (There were additional specifications on what these five paragraphs should look like.) This was obviously not what I was taught in high school and college.

I assume there are these "inconsistencies" because writing is a very hard thing to teach, and that it makes at the very beginning to teach them with a lot of rules and constraints (as in Example III). Then as the student matures, teachers teach students a more refined version of what is considered "good writing." Therefore, many of the rules from earlier are taken away.

My questions:

Is there a general consensus (amongst, say English educators or academics) on how English should be taught? (In particular, if it is fine to use passive voice in one's writing or to have run on sentences?)

Answer 1

As @F1Krazy said, it isn't really an inconsistence. A beginner learner - in any area - is first taught the general rule and trained on a certain logic. Later, as they master those concepts and logic, exceptions and finer details are added in.

I'll give you an example from learning English as a foreign language: first, students are taught that Present Continuous is used only for temporary actions happening now and use it in exercises for that effect. Then, the distinction between 'temporary action now' vs. 'facts, routines and opinions' is added in and practiced until both structure and ability to distinguish between the two from context are flowing well. Later, they are taught that it can be used for talking about future arrangements. Even later, they are taught that it can be used for exageration (you're always making noise).

If all that information were given at one time, it would be too much. Moreover, the use for exageration would clash against the most usual use of 'always' for routines and students would get lost and frustrated. Especially children.

Similarly, it's easier to write a well organised text if you're using short sentences and the paragraphs are draconically rigid. That way, students learn - through practice - to organise their ideas in a clear-cut way. As their ability improves, they won't need such rigidity as they'll know when to use the rules, how to bend them and when to break them as a way to transmit their ideas more accurately.