It’s very hard to get playtesters for anything. It’s hard to get the attention in the first place, then to find people willing to playtest the game, then getting those people to actually play it and then getting them to give useful feedback. So many people are wedded to one system or one campaign that it can be virtually impossible.
I get playtesting done as best I can, simulating scenarios by myself to test out different aspects of the game with different characters. Like editing your own work, this is tricky, as you know exactly what you meant and don’t necessarily see the errors. For similar reason, playing with your regular group is helpful, but not likely to be hugely helpful.
One of the boons of producing material electronically is that it is relatively easy to update it later on, to ‘patch the game on the fly’. It’s annoying when computer games companies do this by not releasing a complete product, but it is useful from a game designer’s perspective when you find things that need correcting.
So, most of the time, no playtesters. I wish it were otherwise, but it’s just not that practical for a small, indie company.