I use 4. With the shift/alt shortcuts I find using 4 is faster than trying to use more, but I could understand why one would like to keep a 5th one in the center.

I see people using 7 or 8 probes at once though and I just wonder, is there some secret technique that makes scanning actually faster with more probes?

On paper 8 would scan twice as fast as 4 when you have more than 1 signature, but the alt key shortcut makes it faster to just use 4 on both sigs.

"Because I fecking can"

Because they changed probing from the old system - now the more probes you have the better sig strength you get.

No, I believe that's response to..

Why are you flying a laser machariel?
Why did you fly a pre-Inferno procurer?
Why did you fly a pre-Inferno procurer with a smartbomb on it?
Why were you mining in an abaddon?
Why did you mine a full can of veldspar with only 4 turrets on marauder and then turn the can blue and announce in local "FREE ORE" while tractoring it around with a MWD on? (and get chased by a equally silly Golem?)

I've just got some really strange looks because of the amount of snorts and laughter this post produced, you sir have just won the most amusing post I've seen all day award.

In before "It takes 4 to operate the handtruck to lug my massive balls around"

It worries me that you have chosen a female avatar, but still need to lug your balls around with a handtruck.....

I succeed quite well (and quickly) with 4 probes; only RARELY do I need a fifth, and that's typically because I wasn't paying attention. Using all 6 or whatever just because you read something about it on the forums is really kinda silly.

Get your Astro skills up to at least L4 on all, use Sisters gear plus Grav Cap, and throw in a bonused ship for good measure, and you don't need to embarass yourselves posting non-sense on the Forums anymore.

Unless you're into that...

I use 4. With the shift/alt shortcuts I find using 4 is faster than trying to use more, but I could understand why one would like to keep a 5th one in the center.

I see people using 7 or 8 probes at once though and I just wonder, is there some secret technique that makes scanning actually faster with more probes?

On paper 8 would scan twice as fast as 4 when you have more than 1 signature, but the alt key shortcut makes it faster to just use 4 on both sigs.

Wait, what's this "alt-key shortcut" thing.... if there's a way to scan faster, I wanna know about it.

Press and hold alt while dragging probes it and it scale them in or out from their relative center point.

And afaik this feature is well over a year old now hehe.

Use 8 probes.
I'll leave this here as a reference as to why:
http://www.youtube.com/watch?v=TisDb8c2aS4

Yes, you CAN use 4 probes to lock down any sig.
That said, it's about as efficient as running L4 missions in an armour tanked drake.