Can an e-way bill be generated in bulk in one go?

yes, you can generate multiple e way bills in one go. For that you need to use bulk e way bill generation tool.

This is an excel template where in you need to enter all your outward/inward supply details.
Once your file ready, you need to generate json file. Further, you need to logon on e way bill portal. Go to e way bill portal >> click on Generate bulk >> upload the json file.

Thats it. In this way you can generate multiple e way bills in one go.