That question cannot be answered in definite terms. Development projects can vary from a 1-lot Single Family home to 20-acre subdivision, to a 4-acre commercial site, etc.
I'm a civil engineer, and for example, I do the civil engineering/permitting for many Gas-Station & Convenience Store. Our fees are not based on the profit or value of the project. Its a per-service fee. I.E., how much design work does the civil engineer need to do. For a Gas-Station with total development cost of ~$1.5M, I will tell you our fees would be nowhere near 33% of that.
Fee for professional services are not typically based on the profit or value of the project. Its a per-service cost. I.E., how much design work does the civil engineer need to do. The requirements from projects/jurisdiction's varies greatly. Also, logically speaking, for whoever the owner/developer of the project is, they have much more risk involved and should deservedly be the ones with the profit to gain.