Everytime you run OFW without a bootloader like Hekate, your operating system will try to make the number of fuses match what it thinks they should be.
For example, if you only have six fuses burnt and update to 7.0.0 without burning fuses using choixdujournx, you will still only have six burnt fuses. If you boot your system normally without using RCM and Hekate, however, then you system will burn enough fuses to bring you to nine burnt fuses, since 7.0.0 wants and expects nine burnt fuses.
The only way to be sure you don't burn any fuses is by installing AutoRCM. This prevents your system from ever starting up without Hekate.