Hi there nalam29,
It appears that you're wondering why it takes so long to update your Apple Watch, and we're glad to provide assistance.
Update your Apple Watch - Apple Support -- Even though your Wi-Fi network may be fast enough, it will also depend on how many devices are already connected, what they're accessing, etc. Also, if you update your Apple Watch using your paired iPhone, the update is first downloaded to your iPhone, then installed on the Apple Watch. Sometimes moving the device(s) closer to your router can speed things up a bit. You can also update your Apple Watch overnight instead.
Feel free to get back to us with any questions or problems you may have.
All the best.