This is an old issue that is unresolved since around 2.4 where it was first noticed. The descriptions for Piece by Piece and Muscle Memory claim these skills increases progress by one third, though this is wrong. The observed results are slightly -but very noticeably- less than that:

Piece by Piece Description:
Increases remaining progress by 1/3.

Muscle Memory Description:
Increases progress by one third.

Expected formula:
RemainingProgress = TotalProgress - CurrentProgress
ProgressGranted = Math.Floor( RemainingProgress / 3 )

Observed formula:
RemainingProgress = TotalProgress - CurrentProgress
ProgressGranted = Math.Floor( RemainingProgress * 0.33 )

Example - Seafood Stew (Level 60*: Difficulty 1116)
Expected: 372. That is: one third of 1116, therefore: 1116 / 3
Observed: 368. This is equal to 1116 * 0.33, rounded down

33% or 0.33 is NOT equal to 1/3 or one third.

In the above example, there is a 4 point gap between the expected result (as advertised!) and the actual result.

Either the descriptions for these skills need to be corrected to reflect this, or the mathematical formula used by the game needs to be fixed to match the description. This may not seem like much, but in some cases, this can make the difference between being able to fit it one more quality action in a routine, or having to do an extra Careful Synthesis II to finish instead.


=== BUG REPORT TEMPLATE ===

Time: Any time
Frequency: Always
World name: Masamune (most likely all worlds)
Character name: Inzoum Zimia
Retainer name: N/A
NPC name: N/A
Monster name: N/A
Class/Level: All crafting classes, Level 60
Party or solo: Either
In-game time: Any time
Area and coordinates: Anywhere
Housing: N/A
Steps:
1. Begin crafting any recipe (higher level recipes with higher difficulty makes this more obvious)
2. Use Piece by Piece or Muscle Memory
3. Progress granted by action is slightly less than one third


Connection Specs
- Type of internet connection/provider: Proximus VDSL2 (30Mbps)
- Modem maker/model number: Proximus b-box2 / b-box3

PC Specs
-=-=-=-=- System Information -=-=-=-=-
SYSTEM_OS Windows 10 Famille 64 bits (6.2, version 9200) (10240.th1_st1.151104-1714)
SYSTEM_CPU Intel(R) Core(TM) i5-4200H CPU @ 2.80GHz (4 CPUs), ~2.8GHz
SYSTEM_CORE_NUM SYSTEM_CORE_LOGIC 4 SYSTEM_CORE_PHYSICS 2
SYSTEM_BIOS G750JM.206
SYSTEM_LANGUAGE français (Paramètres régionaux : français)
SYSTEM_MEMORY 8074.996MB
SYSTEM_VIRTUAL_MEMORY 2047.875MB
SYSTEM_PAGE_FILE 9354.996MB
SYSTEM_STORAGE C:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 372.604GB SYSTEM_FREEDISC_SPACE 155.266GB
SYSTEM_STORAGE D:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 537.797GB SYSTEM_FREEDISC_SPACE 493.749GB
SYSTEM_DIRECTX_VERSION DirectX 12
SYSTEM_GRAPHICS Intel(R) HD Graphics 4600
SYSTEM_GRAPHICS_DEVICE \\.\DISPLAY1
SYSTEM_GRAPHICS_CHIP Intel(R) HD Graphics Family
SYSTEM_GRAPHICS_MAKER Intel Corporation
SYSTEM_GRAPHICS_VRAM 112.500 MB
SYSTEM_GRAPHICS_SHARED_VRAM 3983.438 MB
SYSTEM_GRAPHICS_DAC Internal
SYSTEM_GRAPHICS_DISPLAY_MODE 1920 x 1080 (32 bit) (60Hz)
SYSTEM_GRAPHICS_DRIVER igdumdim64.dll,igd10iumd64.dll,igd10iumd64.dll,igd12umd64.dll,igdumdim32,igd10iumd32,igd10iumd32,igd12umd32
SYSTEM_GRAPHICS_DRIVER_VERSION 10.18.0015.4256
SYSTEM_GRAPHICS_DRIVER_DATE 17-07-15 23:34:24
SYSTEM_GRAPHICS_DRIVER_LANGUAGE Anglais
3.0
SYSTEM_GRAPHICS_PIXEL_SHADER 3.0
SYSTEM_GRAPHICS_VERTEX_TEXTURE SYSTEM_SUPPORT
SYSTEM_SOUND Haut-parleurs (Realtek High Definition Audio)
SYSTEM_SOUND_DEVICE_ID {F5F220A5-403B-41A7-BA31-69D8C73772CF}
SYSTEM_SOUND_DEVICE_NAME RTKVHD64.sys
SYSTEM_SOUND_DRIVER_VERSION 6.00.0001.7535
SYSTEM_SOUND_DRIVER_LANGUAGE Anglais
SYSTEM_SOUND_DRIVER_DATE 24-06-15 21:57:00
SYSTEM_SOUND Realtek Digital Output (Realtek High Definition Audio)
SYSTEM_SOUND_DEVICE_ID {90CE9FB5-AA3E-452F-A25D-D552BB098850}
SYSTEM_SOUND_DEVICE_NAME RTKVHD64.sys
SYSTEM_SOUND_DRIVER_VERSION 6.00.0001.7535
SYSTEM_SOUND_DRIVER_LANGUAGE Anglais
SYSTEM_SOUND_DRIVER_DATE 24-06-15 21:57:00
SYSTEM_INPUT {6F1D2B60-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Souris
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 3 SYSTEM_GAMEPAD_BUTTON 3 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {6F1D2B61-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Clavier
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 128 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {9F401B20-173D-11E4-8001444553540000}
SYSTEM_INPUT_NAME ASUS Wireless Radio Control
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 1 SYSTEM_GAMEPAD_FOV 0
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Laptop Model Name: ASUS RoG
Laptop Model Number: G750JM

Gamepad Manufacturer: Microsoft
Gamepad Model Name: Xbox 360 Wired Gamepad for Windows
Gamepad Part Number: standard model

Browser Information
- Name and version of the browser currently in-use: N/A
- Internet Explorer Version: N/A

Previous bug reports about this issue filed as Insufficient Information:
http://forum.square-enix.com/ffxiv/t...Piece-By-Piece
http://forum.square-enix.com/ffxiv/t...e-slightly-off