Pre made vacuum sealer bags are already made so it saves time. All that needs to be done is put the food into the vacuum sealer bag and vacuum then seal. If you are doing a lot of vacuum sealing at once the pre made food vacuum bags will save time. If this is in a professional kitchen the food vacuum sealer bags will also save on labour. Food vacuum bags vs rolls on price and if you are buying from food vacuum sealers Australia then food vacuum bags are cheaper than rolls. Summary is that you will save time and labour with pre made food vacuum sealer bags. Food vacuum pre made bags cost less than rolls
Cons
Because you can get through the process faster you may need a semi commercial or commercial machine to handle large volumes of vacuum packing and the machine will not over heat. Such as the Status Provac 360.