I am currently teaching a course on Developmental Editing with the UCLA Extension program. (Shameless plug but check out the program 😁). One of the first major assignments I give the participants is to examine and study a single publisher. The goal is to know that publisher "inside and out." While all of the students did a pretty good job, they all made the same mistake that a lot of authors make. They looked at things on a surface level and only focused in on the big issues. What did they miss?
The voice of a publisher is really something that all authors need to look at before submitting any manuscript. I would even go so far as saying you need to know the publisher you want to write for and know their voice before you even start writing. Let me explain what the people in my UCLA course were doing.
They looked at plot and topic. They looked at "mission statements" of the publisher and what they publisher said they like in terms of themes. Yes, these are all great places to start, but it still comes down to the voice.
You will find that the genre of your writing or even the topics you write about show up with a lot of different publishers. HOWEVER... the voice of every publisher is very different. You can pick up a romance novel from Harper Collins and clearly be able to say that is a "Harper Collins voice." You can also clearly hear the difference in the same genre of writing when you pick up a Source Books, Kensington, or Berkley novel. They all produce the same genres and often have very similar descriptsion of what they look for (including word count) but the voice is VERY different.
If you really want to be successful in this business, you need to take the time to really study the voice of the publisher. I promise, it will pay off for you!