Which tense to use when describing a blueprint of sorts?

I thought I might ask here as well.

So I’m writing a paper and I want to define the experimental process. I have two challenges.

Firstly, when I define the experimental process, I want to write it in a way that is independent of its execution, i.e., a generic process definition. So, which tense should I use? Past doesn’t sound right, because it’s actually a blueprint for an experiment and not something that was already done. I was thinking present simple? For example, I don’t want to say “In the first step, participants had to answer the question” but something in the manner of “in the first step, participants answer the questions”. I’m not sure which tense to use.

Secondly, I want to state that the experimental process was executed three times. What noun should I use? I’m using the “instances” noun, e.g., “Three instances of the experimental process were performed across three days”. Is this an OK choice for what I’m writing about? Also, I want to stress that the same experiment was completed three times, once each day and not that one experiment lasted for 3 days.

Thanks for the advice!