A very complicated question that depends considerably on the shooter's style and capabilities. A 26" 20 bore suggests a low swing effort gun with low swing stability. Tight (full) choke suggests long range shooting which generally requires high swing stability to achieve low aiming angle error. But, some shooters have the capability to shoot low swing effort guns well at long range. Shoot some 27 yard trap and see how you do. If you do well, then leaving it tightly choked is a reasonable option. Then, shoot a few rounds of skeet and see how well you do. That will tell you if you (you yourself) shoot well enough to use tight chokes at short range.

You might consider one open and leave one tight.

DDA