One of the biggest RP killers is the mentality of "eh I'll post later".
If you find yourself thinking this, do one of two things:
1. Drop the fuck out
or
2. Post anyways.
This sort have seems to have gotten way off the original topic. But I'll just add some quick two cents. Now this may seem questionable of me, since I've not GM'd here before specifically. But I have elsewhere. So some friendly advice to everyone.
If you're running a campaign, aside from world/lore specific rules, here's essentially the only rules a good GM needs.
1. The GM has the final say.
2. Stay active. If somebody hasn't posted within (insert preferred time here) and haven't explained their reasoning for their absence. The GM will take control of your character, if necessary. (Which can possibly lead to that character's demise.)
And that's it.Yes, it's a hobby. But it's everyone else's hobby too, so they kind of need active participants. If you take a week of silence and procrastination to post anything, you're acting selfishly. You've got a life? Congratulations, so does everyone else.
I don't recommend rushing posts either, sometimes you feel sick or in a crappy mood. So explain your situation. That's not difficult at all, granted I'm sure a part of that behavior comes from introversion. But literally any signal, is preferable to nothing...
The best way to resolve any problems that may be legitimate, like a member dealing with a sudden death of a family member for an extreme example. You can use temporary character control, either the GM or possibly whomever the absent player permits to take control. (that's often that's something you can set up in the CS, preferably before it happens.) If you suspect somebody has gone inactive and it feels like a ret-con to just let them vanish from the story. Make a scene where they are killed off, or disappear from the story. (If it's not appropriate genre for death.) A GM, has absolutely no reason to let one or two individual slow/dropped without a word members from ruining the campaign at large. There's literally always a way around it.
If you're a GM that encourages people take entire months to post anything or do anything productive, it's also just as easy to include that (or any possible any other concerns) and address them immediately in your OOC.