I wish Lenny had more to say before he starts repeating himself. I bet he could keep most of them on the line a lot longer ;)
The ducks are priceless, I love the diversion strategy. A lot of Lenny's stuff works because it can be interpreted as appropriate answers to a wide variety of questions. Like his "Good, yes yes..." can be seen as responding to a question about how he's doing, agreeing to a yes/no question, or simply being polite.
It seems that usually Lenny fails when people start trying to get numbers out of him ("how much are you willing to spend?", "how much can you donate", "what's your credit card number", "what's your address?", etc) It'd be nice if Lenny had a way to inject some numbers into the conversation (fairly late in the conversation, after he's done his "world finances" speech), without his response only being applicable to questions about numbers. For example, maybe he could have a barely audible conversation with someone family member in the house, wherein Lenny sounds like he's referring to the phone call and trying to gather information, then starts repeating some numbers ("thirty-two.... oh.... oh?... but the... (mumble mumble...)", then goes inaudible again, and ultimately the person leaves the house thus making them conveniently unavailable for followup. Lenny then returns to the conversation on the phone with some meaningless mumbling or platitutdes, leaving the caller to interpret the numbers that he heard as either the start of the numbers he was asking for (or the whole thing), or contrarily (if he wasn't seeking numbers) a side conversation that has nothing to do with him. Lenny's next response should start off with "yes, yes...."
The caller would surely follow up trying to get more information / the rest of the information that they were seeking, so Lenny's next line could operate on that assumption. Maybe have one of his rambling stories at that point, and then after that he forgets what it was he was saying the person on the line... maybe eventually calls up the family member on a cell phone to get the needed information, getting another mumbly conversation, ending with the family member brushing him off and telling him that they don't have time, that he should talk with (other family member). Giving Lenny an opportunity for more delays and brushoff tactics, plus plenty of apologetic "I hope you're not upset with this old man for taking so much time..." type responses... maybe him having trouble with his cell phone (perhaps even trying to get the operator to offer tech support advice? ;) ), ending with him giving up and having to go dig through files (that could take AGES).... I bet they could go from record conversations in the half-hour range to average conversations in the same range. ;)