I got a rescue adult cocker two months back. We were told she was house trained but on about a weekly/bi weekly basis the accidents began. Only when we are home. When we're out she has freedom to roam in some of the house and there are never any accidents when we get in. We take her out when we get in, when she wakes up, after anything exciting, every hour or two when we're home, 45 - 90 minutes after eating... We've been positively reinforcing when she's goes outside (which she clearly feels proud about!), her food is given on a schedule, etc.
I presume... well a few things 1) this is because she is sleeping most of the time when we're away (which is true) and when we are home she is awake/active and therefore more mindful of the need to eliminate and 2) we just have no clue how she is communicating her need to wee. She sniffs everything all the time and is generally quiet. I've read up on this and the only things we aren't doing is using treats to positively reinforce going outside - so we'll start doing that - and that she cannot be allowed out of our sight when she isn't confined. We won't crate so I've read that my only choice is to have her on a lead attached to me, which we have just started. Poor thing looks confused and I'm certainly going to have a job getting used to this myself.
I'm looking for anyone who's had to do this to offer any advice or encouragement as I'm feeling mixed - happy at the thought that this might help, and displeased to live my home life tethered to my dog when she isn't confined to the safety of the kitchen (where she's never eliminated)!