Writing punishment or incentive?

[FarAwayHills]

DD Y4 hasn't got the best handwriting or spelling and I have been working hard with her to improve things. The main issue with her is that she needs to slow down, take more care and check her work to correct simple mistakes.

I have recently noticed that her writing is getting worse, with old habits of rushing things creeping back. Apparently her teacher makes them stay in at play time if they don't fill a whole page or write X amount in writing tasks.

I understand that she is trying to motivate them through fear of losing play time but in DDs case it she would rather fill a page of badly written work than stay in at break time. Wouldn't it be better to have half a page of quality work and with practice this could be built up over time? I feel like I'm wasting my time.