The only time when I did group study sessions with strangers was on double EXP weekend between the Highpass MM's. To refresh everyone, the MM's had a recharge of 45 minutes but could be completed in about 17, or as low as 15 or 16 in some cases with a sharp group.. lots of free time inbetween (half an hour!).
Normally, I just warned group I was able to spam, along with the reason why, which I saved to a hotkey. It also invited them to put me on Ignore until the start of the next mission if they weren't interested. Most people seemed to go AFK (as they would've it I wasn't spamming anyhow) or join me in spamming. I can't remember anyone actually ignoring, though one guy did say he had 100 in one of the langauges, so I'm not sure why he didn't. No one ever complained.. guess you just need to give a head's up and offer a simple solution to it before starting.