I recommend anyone looking for updates to this mod use this version: https://www.curseforge.com/minecraft/mc-mods/preciseblockplacing
This is a simple tweak mod to improve the vanilla block placement logic.
In vanilla, when you hold down the right mouse button (or your keybind of choice), the game tries to place a block every 4 ticks, regardless of anything else. This can result in annoying behavior, such as double placed blocks, or gaps.
This mod attempts to improve this logic by allowing blocks to be placed instantly when a new location is under the cursor. Example:
Before:
After:
As you can see, in the "After" gif, the placement is much more consistent.
By default, this mod also tweaks double placements, removing them entirely. If the RMB is held down, only a single block will be placed unless the cursor is moved. This can be disabled in the config with the "forceNewLoc" option. Additionally, there is an option to only apply the behavior changes in creative mode.
This mod is client side only. It can be installed on servers, but it will serve no function.