Wyatt,
It is not necessary to put in for reservations (check DFW website).....By doing so though, you give yourself a chance at getting a reservation and better spot on the wildlife area hunting blinds.
After opening week-end and maybe Christmas time, you can always get a blind in the morning.....There's also the lottery draw for blinds after the reservations have picked (about 30% show up of the 100 reservations sent out).....To be in the lottery draw you must sign-up by 10:30 the night before the hunt (Tuesday, Friday nights).....You can also just walk up on the day of the shoot and see what's on the board and pick that way.