One of the best part of learning during post graduate course is to participate in conferences and learning a lot from ones seniors of the same specialty and also trying to present a paper yourself. There would be one "Oration lecture" too which everyone must attend. Updating yourself with the latest developments and recent advances in the specialty is always essential.
Please don't attend a conference or an online lecture only for meeting old friends . Yes, that's an added bonus which you would get in any case. My sincere request to all post graduate students is to present papers and participate in as many scientific sessions and conferences as possible.