I've been a few times over the years and would agree that the summer is a good time to go as it isn't too busy and you can potter about at your own pace. I've been the day before match day as well and it's busier but not hugely so.
I've applied for about 10 of the last applications over the last few seasons and have never been successful. I've only applied for A and B. Have also applied for 2 seats with one of my mates so there's probably a lesson in all of that.