Here are a few signs your proposals might need improvement: 

You consistently score lower than expected on RFPs.
You’re mostly copying and pasting from past proposals (with little customer focus).
If you open your submission to a random page and read a paragraph, it isn’t clear who the customer is or what they need. 
Your win rate is less than 50%. 

If you experience the above, it may be time to work on your content to align with successful proposals more closely.