Let's look at an outside 30 lead. This is someone that can answer the magic questions, why, when and where, but is not going to do something in the next 30-45 days, more like 60-180 days. As long as they answer the 3 questions then they are a lead. Let's suppose someone owns a condo and is graduating school in 5 months and they are taking a job in another state as soon as they graduate. They are a lead they just need a different follow up system. I would put them on a monthly snail mail, monthly email, and a monthly call.
Again you are checking in, Hi, how is it going? The last time we talked you said you were moving in the month of _______, I was wondering is everything still the same? If there is anything I can do call me, btw who do you know besides yourself that is going to be moving that I could be of service to?
This type of lead is actually a good lead, most agents will not follow up that long and you can cement a relationship with them and have a little insulation from competition, I repeat a LITTLE.