Cardboards boxes....a worry

We have always put a large cardboard box, on it side, filled with hay on top of the ledge in Nala's shed...we know she does go in and lie in it. The problem is, she always munches her way through them rather quickly....yes we do get some mess, but she obviously eats it. I am now worrying that this could be harmful to her....she does have a couple of carry boxes also with hay in them if she wants to go in to them....don't think she does....always seems happy to be sitting on her shelf.
I also worry that she doesn't eat as much hay as she should....she has so much hay in the shed, its hard to tell just how much she actually does eat.
I know she has got to be warmer in the shed than in an outdoor hutch, so maybe we could do away with the cardboard box....sorry to ramble on, but any advice would be appreciated

we give ours boxes to play with but i always take them away if the buns start to get carried away chewing them i think a bit of cardboard is ok but not too much

Spenser is a box-chewer, and I do watch out for him eating it. As rabbitmum says, the odd bit is unlikely to cause a problem. If she's eating several inches this would be more of a worry. I have a cardboard box in Spenser's lower hutch, which I would certainly be reluctant to remove before his new hutch cover arrives as it provides warmth as well as stimulation.

As to hay, have you tried different types. My bunny is quite fussy, so I have been getting him sample bags from Animal Magic. I've also tried to cut down his pellet ration to encourage more hay-eating, as I was probably being a bit too generous with pellets. Some would say I still am.

If it makes you feel any better, i have a box eater too.

I can't 'not' give them cardboard boxes as they love them, so i just do. Biccy must of eaten quite a few in his time, as long as they are eating plenty of hay and drinking plenty im sure it would be fine?

Any experts, can you comment?

I make sure the cardboard boxes I use have not been used to transport anything potentially poisonous 'just in case' but mine turn boxes into happy confetti and throw it everywhere.

I use a mix of hays and sprinkle in fried herbs to try and make the hay more interesting to rummage through and eat than the box.