A few weeks of suffering through DIY SQL is really the only way to fundamentally understand how the database is working for (or against) you. Once you learn it, it really does become like a second language. You can fade in and out of proficiency based on recency of exposure, but it is mostly like riding a bicycle. One other advantage is you can take it across any SQL platform without a second thought. Many ORMs have provider-specific compatibility woes to contend with.
My process is generally - write SQL to find the best query, then convert the SQL to Knex for integration.
As a simple example, say you are making a simple query to the db, but in some edge cases you need another column to be selected. Knex lets you do this:
let query = KNEX("table").select("col_1")
if(weirdCondition) {
query = query.select("col_2")
}
const rows = await query
SELECT col_1 FROM table
SELECT col_1, col_2 FROM table