Learn Spanish (Latin America): El director confesó que solía llorar en cada graduación. - The principal confessed that he used to cry at every graduation.

In reported speech, when the reporting verb is in the past (like confesó), a statement originally made in the present tense shifts back one step into the past. So, the present tense suelo backshifts to the imperfect tense solía.

What if his original words were already in the past, like Solía llorar (I used to cry)? Would the sentence change?

No, the sentence would look exactly the same! When an original quote is already in the imperfect tense, it doesn't backshift any further in reported speech. It simply stays in the imperfect. You have to rely on context to know if he meant 'I usually cry' or 'I used to cry' at the time he confessed.

Why use solía llorar instead of just saying lloraba?

Both are grammatically correct and translate to 'used to cry' as a past habit. However, using the verb soler followed by an infinitive (llorar) strongly emphasizes that this was a routine. It leaves no doubt that it happened repeatedly, whereas lloraba is just the standard imperfect and could sometimes mean 'was crying'.

Can I use todas las graduaciones instead of cada graduación here?