Barrel Aging Reds

That all depends on the size of the barrel, the age of the barrel, how many batches have gone through it before, etc.

Seriously, smaller barrels, like those meant for kit sizes, like 5 gallon barrels, can so easily over oak a wine for about the first 4 or 5 kits, that yes, you can certainly omit the oak. Remember also, that as a barrel starts to get neutral, you'll need topping up wine as the wine will be in the barrel much longer and barrels breath and evaporate wine. That's why I mentioned a 5 gallon barrel as opposed to a 6 gallon barrel. 5 gallons gives you 1 extra gallon to top up with, and you'll need it by the 6th or 7th batch. Also, you never leave a barrel empty! But don't fill it with water, or all you are doing is losing all that oaky goodness you paid for into the water.