How does Large Unit Infiltrations work?

[Psieye]

$250 at the GTS for "6,7-man squad infiltration time reduced". Does that mean a 7-man has no infiltration penalty like a 5-man? Does the 5-man squad remain the same after buying that? Is an officer (of a certain rank) required to make that discount kick in?

If I skip that one and go straight for "8,9,10-man squad infiltration time reduced", do I get the benefit for 8-man squads but not for 7-man?

[Noober]

$250 at the GTS for "6,7-man squad infiltration time reduced". Does that mean a 7-man has no infiltration penalty like a 5-man? Does the 5-man squad remain the same after buying that? Is an officer (of a certain rank) required to make that discount kick in?

If I skip that one and go straight for "8,9,10-man squad infiltration time reduced", do I get the benefit for 8-man squads but not for 7-man?

First upgrade cuts infiltration penalty of 6 man's squad close to 5 man. Somehow like 5d20h for 100% without a boost (legend).
It basically means that you can now deploy a 6 mans squad instaed of 5 and it's usually unlocked by the time you are out of E.Light missions and start doingmostly V.Light. That makes it (for me) THE MOST powerfull upgrade in GTS - just sell everything and bye it as soon as it's avaliable.

As for other upgrade - it cut's like day or two from 8 mans inf timer.
But in order to uncover the true power of this upgrade and have an ability to deploy a 8 mans squad in regular GOP with like 6 days timer you should have an GSGT Officer with Infiltrate perk which is a tool of a late game.
And you really don't need that many soldiers until then for most missions except for UFO (which are too rare to spend $250) and HQ/Golden Path (which are without a timer).

[Psieye]

Time to just make a table and see how things vary. Trying this on an HQ (Commander):

=== Default: Squad Size Modifier and Infiltrator effect ===
4-man = -1d 5h -16h
5-man = 0d 0h -17h
6-man = +1d 12h -21h
7-man = +3d 0h -1d 1h
8-man = +4d 19h -1d 6h
9-man = +10d 19h -1d 23h
10-man = +18d 0h -2d 17h

=== Tactical Infiltrations: Squad Size Modifier and Infiltrator effect ===
4-man = -1d 5h -16h
5-man = 0d 0h -17h
6-man = +0d 18h -18h
7-man = +2d 6h -23h
8-man = +4d 19h -1d 6h
9-man = +10d 19h -1d 23h
10-man = +18d 0h -2d 17h

=== Large Unit Infiltrations: Squad Size Modifier and Infiltrator effect ===
4-man = -1d 5h -16h
5-man = 0d 0h -17h
6-man = +1d 12h -21h
7-man = +3d 0h -1d 1h
8-man = +3d 14h -1d 2h
9-man = +8d 17h -1d 16h
10-man = +15d 0h -2d 9h

=== Tactical + Large Unit Infiltrations: Squad Size Modifier and Infiltrator effect ===
4-man = -1d 5h -16h
5-man = 0d 0h -17h
6-man = +0d 18h -18h
7-man = +2d 6h -23h
8-man = +3d 14h -1d 2h
9-man = +8d 17h -1d 16h
10-man = +15d 0h -2d 9h

*** Conclusion ***
Tactical Infiltrations = -18h to 6-man and 7-man
Large Unit Infiltrations =
-1d 5h for 8-man
-2d 2h for 9-man
-3d for 10-man

Infiltrator + Tactical Infiltrations = no penalty to 6-man and +1d 7h for 7-man