it does make sense! and you actually kind of answered your own question. this is something i'm going to touch on when i eventually get to the patreon post about settling down to actually write, but as a rule, we deliberately set out to not have two consecutive sentences start with the same word, barring deliberate repetition for emphasis. same rule for the start of consecutive paragraphs.

i think it can feel automatic and intuitive to start sentences with a subject and then follow with the action. but you're right that it can make your writing feel flat. there is a rhythm to reading something, and if the sentences are all very similar, it all blends together.

the way you fix this isn't to change what is happening in your story, but to learn how to rearrange sentences to give them variety. i will use a section from chapter 1 of tsgel as an example. this is what it could have read like if we'd allowed every sentence to follow that basic structure:

"Chan had travelled a good deal as the Intergalactic Ambassador for Selene I, but he’d never been out to this particular system before, and certainly not to this planet. He’d never felt such pressure to appear appealing and put together as he did today, not even on his diplomatic missions. His cousin Minho would gleefully call it the nerves of nuptials.

He tried futilely not to sweat, nor cringe every time they passed an open window, of which there were many. He worked, also, to not squint around like an idiot. He'd been on glaringly sunny planets before; he’d been to Halcyon, and discovered upon arrival they had two suns, which just seemed absurd to him."

the writing above isn't bad, but it does feel flat, because even though the sentences vary in length and the information they're conveying, they follow a very similar rhythmic beat. so it feels repetitive.

compare this now to what was actually put into the chapter:

"As the Intergalactic Ambassador for Selene I, Chan had travelled a good deal, but he’d never been out to this particular system before, and certainly not to this planet. Even on his diplomatic missions, he’d never felt such pressure to appear appealing and put together as he did today. The nerves of nuptials, his cousin Minho would say gleefully.

So he tried not to sweat, nor cringe every time they passed an open window, of which there were many. He worked, also, to not squint around like an idiot. It was not his first time being on such a glaringly sunny planet; he’d been to Halcyon, and discovered upon arrival they had two suns, which just seemed absurd to him."

you can see that in many cases, all that we did was simply put the second half of the sentence first. this doesn't always work and it isn't good to do it with every sentence; you can and should sometimes start a sentence with a name or a pronoun. it's just one trick of many to pull out of the arsenal in the quest to vary your writing. sometimes you will have to sit and think about how to rephrase a sentence utterly. but there's no sentence that can't be redone. i really don't think of the "no repetition" thing as an unbreakable rule, but if at all possible, we do try to abide by it.