At my own home I do early routine cleaning and maintenance which runs about 100$ a year, so wondering if this can be done every 6 months or every year to clean the drain pan, filter, etc. at what frequency? 

Also I'd suggest if you are going to mail, it's better depending on who you are mailing to, to mail 6-8x a year to the same people, vs more people, but less frequency. 

I've only ever sent direct mail to specific houses I've seen were vacant or otherwise was interested in.  And I've had pretty good results with that with just hand written letters and envelopes, with a fridge magnet. ...

Some investors might balk at the percentage but when you factor these are low income areas and the rents are low the PM isn't making much for all the drama.If you were a PM and could manage an asset in an upscale area instead for say 8% of 2,000 rent that is 160 a month.13% of 600 rent is 78.00 a month and you are dealing with double bookkeeping, high frequency of damage and evictions, multiple trips and constant monitoring of the asset to keep it performing etc.So it's easy to see why many PM companies will not even consider these places.

Timing is something that I can't really control other than frequency of mailing.What message have you found to be most helpful that turns your "yellow junk mail" into wanted mail which provides a solution to the right person?

The commission per transaction I am at that level but not the frequency yet.2 properties a month closing isn't killing yourself either.

Liquidation rights, voting, distribution frequency, etc. all need to be considered.

Does the frequency with which this could occur matter?

I guess frequency is what I question.

Or you can log in to your bank portal and manually download the transactions once a month or any frequency and they will export as a download file into your software the same way.