Generally, this doesn’t matter Much. But, with theme using a Grid layout for home and archive page its important to have the right no. of posts on the homepage so that everything fits in nicely. For Example our Themes Sixteen and InkNess use a Grid Layout. So, users want to fill the Grid Completely, i.e. each row should contain the same no. of posts. I am sure you understand what we want to achieve by now.
WordPress has an inbuilt setting which allows you to change the no of posts on archives(home page, search results, category, etc).
Go to Your WordPress Dashboard. Under Settings, Select Reading.
In the Reading setting there is an option which lets you change the no. of posts. Default value is 10, you can change it to any value you want.
Note: If you have sticky posts, then those sticky posts will show in addition to the 10 posts. For, example if you have 2 sticky posts, then you will see 12 posts on the Homepage, but not on other pages.