I conducted an experiment with POS (1020spd).
I haven't received a POS in months and it was annoying. I tried different options, changed addresses, waited, waited... Began a new series of tests.
I installed a wallet at work. After that, every second day POS started coming.
I used to have POS on my home computer when a miner worked. When I connected another purse and another three miner - POS stopped coming.
There are 2 pre-output:
1. Several identical open wallets for POS do not interfere with each other!
2. For POS need clean Internet!!! Not necessarily fast. He should be doing nothing.
For week I caught 2 POS.
Testing further.

ps. at the first POS since the beginning of the experiment, 1020 coins were divided into 2 inputs of 510. On the second one the entrance was divided into 260