Dog not taking to house training.

[C_Caballero]

We recently adopted a 1-year old pup from a shelter, and we've been having trouble with her doing her business in the house.

She was a stray before she was brought to the shelter, so at first we thought that she just wasn't used to holding her bladder and that she would just need to practice. However, she doesn't have a problem holding it. She can go 8-10+ hours at night without any accidents. We don't think it's fear, as she's not very meek or nervous around us. We've tried crate training and umbilical training, and she's gotten better, but she still has fairly frequent accidents, with both urinating and defecating. Right now we're taking here out every few hours, but our schedules can get busy and we won't always be able to maintain such frequent walks.

I've checked her medical history provided from her checkups in the shelter. She doesn't seem to have any conditions or issues.

Does anyone have any idea of why she's still having accidents, and any advice for correcting her?

Thanks in advance.