Using multisite to develop then export to a single install is a bad idea. For one multisite behaves different than a single install and you want your dev to as close to the production as possible.
It’s also a pain in the a** to manually export the right db tables then import them into a new database.
For developing locally I only use 2 or three WP installs. Your mainly working on theme files so just create a new theme for each project and you can even use one dev database and change the table prefix in wp-config.php so so you don’t have to create a new database each time.
See this answer for complete details on a nice streamlined local dev system to use.