A broad rule of thumb says that about one-third of your backlinks should point back to your homepage, while two-thirds should point to other pages. However, this is by no means an ironclad rule and your deep link ratio will depend on a number of factors, such as your domain age, link profile and industry.
For example, if you are in the retail industry, you will be well served by links to your inner products page or the reviews page. Since your users might have a purchasing intent, they’d want to see those pages, so why hide them, right?
If you are a health and fitness coach, and sell organic food, you’re essentially selling three things: your brand image; your coaching services; and your organic foods. In this case, you will be back linking your homepage as much as you would back link the inner page of the products that you’re selling.