man i changed the filter for each syringe full i filtered, i did a big batch, filled syringe, filter, sucked up again, new filter, maybe i did it with 3 filters, dont remember but yea man be careful, why not be safe?
I always suggest having atleast 4 filters on hand for backup. A .45 to filter it through the first time, then a .20 to filter it through the second time. Then just get a backup of each to be safe.