Build to last wrong numbers

MisterEnot

• PC, 4.3.1
• While using perk Build to last lvl.1 (30% add) I use First aid kid (24 charges).

So in theory i must have 24 + (24*0.3=8) = 32 charges (2 full heal). But in practice - it was NOT enough for 2 full heals (near 1.8 was).

• use Build to last and first aid kid. Try to heal yourself twice.

Also check enother lvls of this perk. thx