Popular oppinion regarding sd card sizes in both slots

[MarkLewis]

Hello,

What's the popular opinion regarding the two card slots? Assuming you are using the 2nd slot as a duplicate backup, which is what I plan to do, do most people stick to the same size card in both slots? I've read that it's good practice to put different sizes in. For example, a 64gb in slot A but a 128gb in slot B. Presumably so that the recording continues whilst you're swaping over the smaller card when it's full?

Tbh, as I'm just starting out (with the FS5), and I've just spent about £300 on 6x 64gb cards (M series), which might be sufficient for a full days filming if I were to just use 3 cards in both slots. But I was planning on having 4x 64gb cards for slot A and 3x 128gb cards for backups in slot B, but I just can't run to the cost of the 128gb M series cards.

However, now that I have 6x 64gb cards (and they are cheaper than the larger cards), should I continue to puchase this size card or aim to buy a 128gb for the backup slot?

Thanks.