Ive seen a couple people put 4 probes instead of 3 on gas and i know they didnt do it on accident. Does having 4 probes on gas really help mine faster? If so, is it more effective then 3 on gas?

If you were able to mine gas at a speed of 3.1 probes per gas mine, it'd be perfect. Obviously you only put the 4th one on if you need to get gas urgently and a tiny bit faster.

3. Unless you're on katrina as Terran or Protoss then your main needs 4.

Depending on the mineral placement theoretically you could lift your cc closer xD

Ah yes, the infamous (at least amoung mappers) gas issue. If the gas is placed either directly above or 1 square to the left of directly above, then you only need 3. If it is placed directly to the left, you also only need 3. All other directions need 4.

0- best gas position
C-command centre.
- - Dirt

----00
------
0---C

If you check all the recent pro maps, all of the gas geysers in their mains either are to the left or aboev the starting point. Katrina is an exception because they needed the rotational balance for the gas. They just made it so 4 workers are needed at every starting point as to not hurt the rotational balance.

I'm going to be a fag and mention:

Building placement to improve mining.

hmm? I dont build pylons and shit that blox my gas from being harvested

You can make it mine faster though too, althought it's not a big deal. Everyone here pretty much covered it.

Buildings placed next to gas mining will actually slow mining. It's a proven fact.

Double post X_X

May I have a url?

Depends on the actual placement of the building, and how it changes the worker path.

http://www.panschk.de/mappage/comments.php?mapid=1481
You can test the problem (including buildings) using this map.

4 on ure gas will make it goes faster

The difference between 3 and for is so insignificant, it almost doesn't matter..

Katrina needs four though in the main

Bah, I feel as noone has been listening to me. I'll write it shorter for everyone.
If the gas is placed in the closest distance possible to the top or to the left of your cc/hatchery/nex, then you only need 3 to mine at completely maximum effeciency. At the other positions, you need 4 but this will only matter in ZvZ where even just a hundred more gas is crucial.