Dunno the point of the thread, but saying Minato doesn't have great chakra reserve is laughable
- Spent entire night maintaining Kyubi in Kushina
- Shunshin and Multiple FTG either to save his son, kushina and so on
- Warped Kyubi's TBB(S/T barrier)
That was before even fighting Obito.
- Later he used multiple FTG either to escape Obito's warping, escape his chain and finish him with the version2 combined with Rasengan
- Used other FTG and shunshin while coming back to the village and stop Kyubi's Bijudama
- Summoned Gamabunta(part1 Naruto needed Kyubi's chakra to accomplish it although he had huge amount of chakra),
- Warped full Kurama(bigger than all tailed beasts, infact comparable to Perfect Susanoo in size) and his formed Tailed Beast bomb. Also before that, taking Kushina and his son to warp them to safety(to avoid the TBB's blast)
- Shared some part of his chakra inside Naruto
- Performed 2high level sealing techniques(Shiki fujin and the double Shishou fuin), used another summoning jutsu(summoned Gerotora) to give him the seal
Also he had no reason to split his chakra in half when he needed to focus on the enemy in his sight, already knowing on the other side, Hiruzen could handle the situation meanwhile. He already knew the battle wouldn't take long since he noticed the opponent didn't want a long battle and it indeed didn't last long. 1minute at most.
It doesn't matter how much chakra you have. What is important is the purpose of the use of said chakra. You can't just waste chakra uselessly and Minato is the last type of person to do such a thing especially in his situation(having 2Hokages in a village). Even Naruto was warned against using clones when they realised it would be for nothing:
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