I get it. My boy jumps from game to game as well, probably some of the same ones yours enjoys. (Now if only mine would get some sleep and stop over-sleeping his alarm for w***.)
...We still play PnP together 2-3 times a month but that takes a lot of prep time and effort from me, its fun but its not as relaxing as DDO most times, especially when they choose to do something I wasn't prepared for which happens at least once a session. Like the last time we played they were up against a bunch of corrupted plant creatures and my daughter just decided nope she wasn't going to fight she was going to take a walk in the other direction... by herself... away from everyone. So she took her walk, tripped down a shallow ravine, attracted unwanted attention and ended up chased and attacked by a warg and only saved at the last moment. Hopefully she learned the never split the party lesson. Or the time before that when the hasted evil bard bandit leader almost got away but my son's enraged orc barbarian decided what-the-heck he was going to throw his greatsword like a spear at the bad bard's back in the distance... then rolled two 20s in a row. So now the party knows more about the big bad and the henchman didn't escape to warn him. Or the time my hubby's cleric used a combo of a spell, and a persuasion roll to turn the tide of battle with some goblins by convincing half of them to worship his deity. Now there's a small tribe of goblins that worship the deity of luck and travel and because that would totally appeal to that deity he guides them around to other goblin tribes to convert them too. ?!? what the heck?!
Those sound epic. As the main DM for my early groups, I totally get it about improvising off the cuff moments. It's also where some of the great memories/stories come from years later.