It also has config variables for the following:
"ChargedStaminaMult": 1.0, - multiply the stamina used for the adjacent filling by this amount (set it to < 1 for less stamina use).
"VolumeMult": 1.0, - multiply watering can capacity by this amount.
"WaterMult": 1.0, - multiply number of adjacent tiles watered by this amount.
"FillAdjacent": true - water adjacent tiles while charging the watering can by holding the tool use button.
It also works with Connected Garden Pots to let you water multiple adjacent garden pots at once.
Technical
Requires SMAPI, uses Harmony.
Compatible with Mod Updater for automatic updates.
Code is at https://github.com/aedenthorn/StardewValleyMods.
If you want to complain or ask for help or help me test my mods, you can visit my Discord server.
A list of all my mods for Stardew Valley is available at https://www.nexusmods.com/stardewvalley/articles/895.