Should I save up Skill Jewels for rogue servants?

[Sire]

I've heard some rogue servants have to have their skills acquired in a time limit, should I be saving my skill jewels for them or am I safe to use them on Iori and Saber?

[VertVentus]

Yeah, you can't complete their skill trees otherwise. More invested skill points means you can complete a tree at an earlier level.
https://gamefaqs.gamespot.com/boards/391357-fate-samurai-remnant/80585320

• The level cap is 100 (Reminiscence: Vile Serpent is 4515 EXP) and you can farm Skill Jewel (Fragments) from human enemies with Loot Up +N.
  
• Iori needs 215 skill points from Skill Jewels to complete his tree assuming you grind to Lv. 100. He'll also need a certain amount of skills obtained with other Servants to complete his trees.
  
• Saber needs 260 skill points, but you can get ~40 exciting spots for a skill point each, and are farmable in NG+. When you complete a Servant's skill tree, it gives Iori bonus stats. Saber Center = DEF +20, Saber North = TEC +20, Saber Southwest = ATK +20, Saber Southeast = ???. 30 Saber skills are required for Iori's Void tree.
  
• Rogue Lancer needs 50 skill points and awards Iori TEC +20. 11 skills are required for Iori's Fire tree.
  
• Rogue Archer needs 55 skill points and awards Iori ???. 11 skills are required for Iori's Wind tree.
  
• Rogue Rider needs 50 skill points and awards Iori MAT +20. 8 skills are required for Iori's Earth tree.
  
• Rogue Caster needs 85 skill points and awards Iori MAT +20. 13 skills are required for Iori's Wind tree.
  
• Rogue Assassin needs 55 skill points and awards Iori ???. 11 skills are required for Iori's Void tree.
  
• Rogue Berserker needs 60 skill points and awards Iori ???. 11 skills are required for Iori's Earth tree. He leaves somewhere in Ch. 3, but you have to do NG+ anyway if you wanted to complete his skill tree.
  
• Rogue Saber needs 40 skill points and awards Iori ATK +20. 11 skills are required for Iori's Water tree. You had to choose Ch. 3 Todoroki for his Digression, he joins in Ch. 4 Fight Tsuchimikado Yasuhiro Rat Route, then leaves in Ch. 5.

The total is 215 + 260 + 50 + 55 + 50 + 85 + 55 + 60 + 40 = 870 minimum skill points.