There are three "stops" in total (the first base, second base and then the final where you finish). Considering the time it takes to finish one full run (40-50 real life minutes in my experience), your best shot is heading over to ch 1, join the lag-fest and try to get at least one voucher between every stop while ensuring that none of the wagons break. Getting more than one voucher per run is "unnecessary" since all you get by having more than one is a random buff potion for having at least ten base-vouchers, but you should still of course kill enemies to ensure that your wagons don't break and... well, if you don't pick up your vouchers then they'll stay on the ground and contribute to the lag. It's also worth mentioning that all your vouchers will disappear once you talk to the NPC in the corresponding base, so if you have 20 2nd base vouchers when you reach 2nd base, you won't have any left when you start heading for third base.
So yes, do it a bunch. Whether you save the vouchers or not is up to you since you won't get any big benefits by having more than one, but I suppose keeping at least one could be helpful if you're not sure that you can get at least one kill during your next successful run.