Are your cams writing the uSD cards to full capacity or are they only filling partially? Full HD continuous recording on 256GB should result well in excess of 24 days.
See the topic links in my post above, especially this one:
There is a problem with the cam being able to use the full capacity of a uSD card over 128GB. Right now the cost of a massive uSD isn’t justified if the cam can’t use all of it.