Diary - How to use proper tense for writing academic paper?

When I had the paper I wrote this time proofread for English, embarrassingly, there were tons of corrections about tense. Honestly, I didn’t really know which tense to use for each sentence. In fact, even when speaking I used tenses every which way, so there were plenty of cases where the other person couldn’t understand me. But a paper lasts forever, so I should use the correct tenses.

These are five rules I received from the proofreading reviewer; honestly, I’m writing them down to remember them myself.

1) The present simple (continuous) when putting forward a theory/design or stating facts

2) The past simple (continuous) for writing about methods, results, discussion, or referring to directly cited information (e.g. “Smith et al. [1] reported that…”; “The best method so far was reported by [2]”), or referring to past events with a specific timeframe (e.g. “In 1997, the PM2.5 concentration was only 12 µg/m3.”).

3) The present perfect when referring to indirectly cited information (e.g. “It has been reported that….. [1].”), with certain words (e.g. “Recently, it has been stated that…”), or connecting a past event to the present (e.g. “This method has been chosen by researchers as the best in the field on many occasions”).

4) The past perfect for a past event before another past event (e.g. “We observed that the mice had already eaten the food.” “Smith et al. [1] reported that the ship had already left the harbor.”

5) Sometimes one rule cancels the other out. E.g. You should use the present perfect with “Recently” unless you are directly citing (e.g. “Recently, Smith et al. [1] reported that…).