Agree with Bruno that 10mb is a reasonable size. SDM is not there to save your users holiday video but you have to adapt for your organization specific.
I will also suggest that you are limiting the extension allowed there depending on your repository type.
i.e. only allow picture extension in the images repository like: !gif,jpeg,jpg,png,bmp or any other you like.
Best security practice is to deny all and only allow what is necessary but you will have to compromise this with your UX.
You for sure want to disallow any executable files like .exe.vbs and others
Just my 2 cents,
/J