Yes, the sentence "I usually indulged in ice cream when I was a kid" is grammatically correct and makes sense. It means that when you were a child, you frequently allowed yourself to enjoy or consume ice cream, suggesting that it was a favorite treat or something you enjoyed regularly during that time.

It's not wrong, though I'd also suggest using the following structures for past habits: - I used to indulge in ice cream when I was a kid. - I would usually indulge in ice cream when I was a kid. Hope that helps!

To indulge is a treat so using “unusually” doesn’t sound right to me. “Often” would be better.

Yup that’s correct. Though the word usually makes it slightly awkward from my perspective but it is correct I’d usually indulge… I would usually indulge … I indulged ..

To be clear, if you usually did it, this means you had ice cream most nights, as opposed to just doing it often.