Just my personal opinion, if you are using dried food like FM, a constant circulation within your dosing container is a must if not all the food will settle at the bottom and you are not getting anything into your tank...
Same with freezing a huge quantity in the syringe and thaw it overtime, it your food will settle at the bottom or should I say "side" of the syringe...
Freezing the food is good if you plan to feed manually when you are home... just drop it in like cyclopeeze and let it melt and disperse in the water...