How many orbs do you spend on legendary ban

Zero. The chances of pulling the unit that you want are hamstrung by the fact that they share the same color as 2 other units. While those other 2 units may still be "good" units there's usually still only 1 or 2 that i want or want more of from the banner. I usually wait to pull till i have a better idea of what i'm going to get.

Fjorm: 120 orbs, 1 Ayra and 1 Brave Lyn

Gunthra: I don't remember, 1 Gunthra

Ike: 53 orbs, 1 L!Ike, 1 S!Robin, 1 Takumi on the same section

Ephraim: 125 orbs, 1 Gunthra

I prefer to pull one 5* and its done.

I always do a full section, and then snipe 2 colors, works for me

300 orbs total spent, basically full pulled on every summon

2x Mia
2x Legendary Ephraim
2x Summer Corrin
2x Dorcas
Shiro
Performing Olivia
Jaffar

Used 4 orbs on Legendary Ephraim banner.
Got Legendary Ephraim on free summon and mia on only red orb in the circle. Stopped afterwards, was sure I wouldn't get anything anymore.

My luck is the same as yours. I think I spent 300 each and the last two legendary banners and got 4 5* on each, none of them being the one I wanted and only one having good IVs. Got up to 10.5% pity rate on the last one. Frankly, I don't think I'll bother with anymore.

THE 8% IS A LIE!

In general the only times I *need* 5 stars are when a new arena season starts with new units, and tempest trials. Typically for those summons I pull until I get a single 5 star and then save my orbs. After that I go all out on legendary or hero fest banners as they're the most likely to get ya +10 on 5? uniques. But that's just how I do it.

First one (Fjorm) Idk like 300+, there were so many I wanted from that banner
Gunnthra: only like 40, didn't rly want anyone
Ike: Like 200+
Ephraim: 150 ish

Fjorm: Like 140 i think... I got four 5* with that.
Gunnthra: Nothing, only free summon, no one interested me in this one.
Ike: Dont remember.. around 200 maybe... got five 5* (none of them Ike lmao)
Ephraim: At first i spent 90 and got three 5*, but then I gave into temptation cuz i wanted PA!Olivia and spent 130 more orbs only to get two S!Gaius haha...

And if inigo is in the next one im spending everything >:(

Fjorm Legendary Banner (Used 100+ orbs)
Goal: Hector, Bride Cordelia or Brave Lyn
Received: 2 Deirdre and a Genny
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Guunthra Legendary Banner: (Used 40 orbs)
Goal: Any of the RED focus units.
Received: 2 Sigurds
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Legendary Ike Banner: (Used 30 orbs)
Goal: Any of the RED focus units except Siegbert
Received: 1 -atk Siegbert
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Legendary Ephraim Banner: (Used 35 orbs)
Goal: Any of the Green focus units.
Received: Nothing.

Fjorm Legendary Banner (Used 85 orbs)
Goal: Bride Cordelia, Genny, Brave Ike
Received: Hector
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Guunthra Legendary Banner: (Used 45 orbs)
Goal: Any 5*, really.
Received: jack shit.
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Legendary Ike Banner: (Used 25 orbs)
Goal: Any Blue 5* unit, and PA!Azura
Received: diddly squat.
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Legendary Ephraim Banner: (Used 25 orbs)
Goal: Any of the Green focus units.
Received: Dorcas x2.

1st: spend about 160 Orbs without getting anything (no 5* s and not even decent fodder), but then got Ayra ATK+/RES- and Ike+ ATK+/HP- with the next 40 Orbs...Ike somewhat is useless now with all the other Ikes

2nd: Got a Broy with 35 Orbs (not great IVs but I did merge him into my Broy SPD+/DEF- anyway)

3rd: bad IV Fjorm for 45 Orbs

last one: Dorcas DEF+/RES- and Gunnthrá SPD+/DEF- for about 90 Orbs

...so six 5*s for more than 350 Orbs...not a great bang for the buck (especially while getting ridiculous few good fodder 4*s and about 60% 3*s)...but at least nearly all units had nice IVs.

less than 40 on Ephraim banner
I'll probably spend everything I have when Jakob and Henry become available (I need better IVs)