Hanbali School  Source: Al-Mughni by Ibn Qudamah
Unintentional Mistake: "If a person doubts the number of prostrations, he should act on the lesser number and perform Sujood al-Sahw." (Al-Mughni, Volume 2)
Intentional Mistake: "Deliberately omitting a prostration nullifies the prayer, necessitating its repetition." (Al-Mughni, Volume 2)
Neglectance: "Neglecting prostrations out of laziness is a grave matter and requires sincere repentance and correction." (Al-Mughni, Volume 2)

Maliki School  Source: Al-Muwatta by Imam Malik
Unintentional Mistake: "When one is uncertain about the number of rak'ahs, he should base it on certainty and perform Sujood al-Sahw." (Al-Muwatta, Book 3, Hadith 101)
Intentional Mistake: "Deliberately omitting a prostration invalidates the rak'ah and the entire prayer." (Al-Muwatta)
Neglectance: "Neglecting prostrations repeatedly without valid reason is sinful and requires sincere repentance and correction." (Al-Muwatta)

Shafi'i School  ​Source: Al-Majmu' by Imam Nawawi
Unintentional Mistake: "If one is unsure of the number of prostrations, they should act on what they are certain and perform Sujood al-Sahw." (Al- Majmu', Volume 3)
Intentional Mistake:  "Intentionally missing a prostration invalidates the prayer, and it must be redone." (Al-Majmu', Volume 3)
Neglectance: "Neglecting prostrations is a serious matter requiring repentance and making up missed acts of prayer." (Al-Majmu', Volume 3)

Hanafi School  Source: Al-Hidaya by Burhan al-Din al-Marghinani
Unintentional Mistake: "If one is in doubt as to the number of prostrations he has performed, he should base his actions on what he is certain of and then perform the prostrations of forgetfulness (Sujood al-Sahw)." (Al-Hidaya, Volume 1)
Intentional Mistake: "Deliberately missing a prostration invalidates the prayer, and it must be repeated." (Al-Hidaya, Volume 1)
Neglectance: "Neglecting prostrations out of laziness or carelessness requires repentance and making up the missed prostrations." (Al-Hidaya, Volume 1)