Q:

Gersonides’ Largest List of Lessons

What is the number of most amount of lessons Gersonides presents at once in his Tanach commentary? I find these lessons very interesting and would like to where the biggest cluster of them is to be found. 

A:

The largest cluster of lessons is 67. This occurs in a section of commentary covering the large majority of the book of II Samuel.

Now for some more details:
We have commentaries from Gersonides on the Scriptural books of Genesis, Exodus, Leviticus, Numbers, Deuteronomy, Joshua, Judges, Samuel, Kings, Chronicles, Daniel, Ezra, Nehemiah, Job, Proverbs, Ruth, Ecclesiastes, Canticles, and Esther. Gersonides used the "lessons" system in all of those commentaries except for Job, Ecclesiastes, and Canticles. The largest cluster of lessons in each book is as follows:

Genesis - 36
Exodus - 24
Leviticus - 26
Numbers - 21
Deuteronomy - 26
Joshua - 14
Judges - 22
Samuel - 67
Kings - 43
Chronicles - 22
Daniel - 33
Ezra - 7
Nehemiah - 24
Proverbs - 20
Ruth - 16
Esther - 51

All the numbers mentioned here are specifically referring to numbered lessons. At the end of each section Gersonides says something along the lines of "the lessons from this section are X", "the lessons from this section are many", or the lessons from this section are as follows". He then proceeds to say "the first lesson is", "the second lesson is", etc. The numbers here are based on the number given for the last lesson in each cluster. For example, by the last lesson in the largest cluster in the book of Samuel, Gersonides says "the 67th lesson is...". 
Sometimes Gersonides doesn't list any lessons, noting that the lessons are already evident from what he has explained in the commentary proper. Other times he mentions additional lessons but not as part of the numbered lists. I only counted lessons that were explicitly numbered as part of a list.
On some occasions Gersonides notes that some of the lessons are redundant, or that the present list is in addition to the lessons in a previous book. Again, I only counted lessons that were specifically numbered in a given list.
Gersonides's lessons can be broken down into four types:

Lessons in Character traits (במדות)
Lessons in ideas or beliefs (בדעות)
Lessons in commandments (במצות)
Unspecified

The first two categories are very common in the narrative portions of Scripture, while the third category is prevalent in the portions of Scripture that actually detail commandments. Lessons in this category are further broken down into the different principles of the commandments (שורש) which are given as a numbered list within the numbered list of lessons. For example, Gersonides will say "the third lesson is in commandments... the first root is..." These lessons are therefore much longer than the other lessons – some have them having a couple dozen roots – and feature most prominently in the book of Exodus. However, even a lesson that has 20 roots listed within it is still referred to by Gersonides as one lesson, and I have counted them that way as well.
Finally, Gersonides was not always consistent in how he arranged the clusters. In his commentaries to the five books of the Torah, for example, he has a cluster after only a chapter or two. By contrast, in some of the other books he lumps a lot of chapters, or even the entire book, into one cluster. Thus, for example, the cluster of 67 lessons in the book of Samuel covers almost 20 chapters while the largest cluster in the book of Genesis only covers 3 chapters.
All data mentioned in this answer is based on the Mossad HaRav Kook editions of Gersonides’s commentaries, namely:

פירושי רלב״ג על התורה
פירושי רלב״ג נביאים ראשונים
פירושי רלב״ג נביאים ראשונים ב׳ כתובים
פירושי רלב״ג איוב - משלי
פירושי רלב״ג על המגילות

