Sage Mode as a method, not an element
Sage Mode is an enhanced state entered through the use of senjutsu chakra. A practitioner brings natural energy into the process of forming chakra, gaining stronger physical abilities and techniques as well as improved sensing. It is a way of using energy, rather than another entry in the list of basic elemental natures.
If those terms are unfamiliar, start with chakra, control and nature transformation. The key distinction is between the energy used to form chakra and the properties a technique gives that chakra.
What balancing means, and what it does not
Senjutsu chakra combines natural energy from the surroundings with physical and spiritual energies. The official Two Saviors recap describes the need to remain still long enough to take in nature energy, and the risk of losing control. Turning that description into exact percentage calculations adds precision this guide cannot substantiate.
Gathering energy can require stillness, which creates a problem in a moving fight. Toad fusion and shadow clones offer ways to separate gathering from fighting. They are workarounds used in the story, not a rule that every practitioner has the same preparation time or duration.
What the state changes in a fight
The same official recap describes Naruto entering Sage Mode after he learns to take in nature energy, then using that power in combat. Those scenes support stronger physical ability, techniques and perception. They do not support omniscience, invulnerability, a fixed power multiplier, or one universal time limit.
When comparing users, consider how they obtain and maintain their senjutsu chakra, as well as what they do with it. The method is shared; the preparation is not.
Where the other pages belong
Naruto’s toad instruction is covered separately in the Mount Myoboku training guide. Kabuto’s snake instruction is covered in the Ryuchi Cave guide. Jugo’s innate absorption and Orochimaru’s cursed seals are a different question, covered in Jugo’s clan and cursed seals. Shikkotsu Forest is named with the other two regions; that naming is not a demonstrated slug curriculum, as explained in what canon establishes about Katsuyu.
Six Paths Sage Mode is a later gift, not toad mastery renamed
Late in the Naruto manga, Naruto meets Hagoromo and receives power before returning to the war. The official Naruto retrospective places that meeting in volume 70, chapter 671, and his return with that power in chapter 673. It is a different context from his training at Mount Myoboku.
The separate guide to Six Paths Sage Mode covers that late-manga form. It should not be used as a new name for every instance of fully mastered toad Sage Mode.