Hi TyeWe've found that mailing the same list 3 or more times at 3-4 week intervals will drive the best ROI.

If the response is still good we will keep mailing that list on a 3 month interval indefinitely. 4.

I found it best to stick to printing in 100 page intervals, not sure why but that seemed to help.

The best advice @Carlo Palomino is to "test"...Do a little research here - there were some great responses above...and then decide which Strategy seems the best one...and then test...If you want to improve your test results - Split test...Divide List and try 2 different intervals to see which one produces the most number of deals...In real estate its all about "Location, Location, Location" in Direct Response Marketing...It's "Test, Test, Test"...What you will find real quick when asking around is there is No "Magic Number"...

I'll not bore you with the details, but I will say that the tests I'm running are statistically significant; +-5% interval with 99% confidence.I hate to harp on the math, but it is quite important to this conversation. 

.- I mailed out my postcards at a quantity of 300-400 and an interval of once a week.

Do you find that the one month interval is the best?

similarly any expectation for property appreciation in a shorter interval than 10 years is ignoring the historical depreciation valleys that have occurred many times.The reality of today’s San Diego RE market is huge initial negative cash flow that will take years of rent increases to make cash neutral.  

Analyze all reports and analyze the work of your support “cast” at the same intervals.