Hehe, welcome. I always use fuses. If you look at the PCB for my mod (posted in another thread here), you'll see two SMD PTC fuses in parallel at the very top left corner of the board. There's two to reduce losses due to resistance. They're actually a backup since the mod senses over-currents and shuts down input power much faster than the fuses can react.
When using a buck converter or a linear regulator, they do have the ability to shut down input power if there's an over-current condition. Boost converters are not able to do that. It's because boost converters can only increase output voltage, not reduce it. So, there is "some" protection with a buck converter or linear regulator. It's still a good idea to add a fuse as a backup. Can never be too safe with these Li-Ion batteries.