Basic Trope: Big craft have little ability to shoot down small ones or missiles.
Straight: A space battleship can't shoot down a swarm of enemy strikecraft.
Exaggerated: A dreadnought, bristling with guns, fills the entire volume around it with flak... and not a single Red Shirt is harmed, much less the hero.
Downplayed: The battleship is normally capable of tracking and destroying many smaller strikecraft, missles, and projectiles at once. However it fails against the new generation's far superior maneuverability, acceleration, and avoidance algorithms.
Capital-grade guns optimized for hurting other capships can't track fast enough to hit small strikecraft.
The tracking system has been damaged / sabotaged, severely hampering the guns' accuracy.
Strikecraft ambush the target and hit as hard as they can before the target can activate the PD and bring it to bear.
Bigger ships "soften up" the PD from afar, allowing the strikecraft to close in for the killing blow.
Point defenses are so good at tearing apart massive swarms of strikecraft, Macross Missile Massacres, even unpowered More Dakka no matter how randomly-dodging, fast-moving or stealthy that the only way to fight is with uninterceptable energy weapons.
The ships have the opposite problem - they are practically immune to strikecraft and missiles. However they fail against the slower tracking high powered guns - logistics force them to be too large to be able to dodge well enough and they can't deflect let alone overpower the projectiles with their point defenses.
Subverted: Improved PD systems can now kill strikecraft easily.
Double Subverted: However, the Ace Pilot still manages to weave through the wrecks of the Redshirt Army and deliver the killing blow.
Parodied: A massive, lumbering snail of a "fighter" somehow is not hit despite having a small country's worth of ammunition thrown at it.
The PD systems have inconsistent performance. Some days they can't hit a single redshirt, other days even namedAce Pilots die en masse to them and still other days it's anything in between.
As the series progresses, we see a Lensman Arms Race between point defences and strikecraft or missiles.
Averted: Point defenses exist, and have a very good - but not perfect! - chance at taking down strikecraft and missiles.
Enforced: The writers want to use Space Fighters in the work, which effective PD would prevent.
Lampshaded: The hero confidently leads his squadron into battle, pointing out how the enemy PD never hits anything anyway.
The capital ship had its PD targeting computers downgraded to a cheaper model so more money could be spent on other equipment.
A Genre SavvyAce Pilot realized that the fighters would get torn to shreds by the capships point defenses, and therefore had an inside man sabotage the targeting systems.
Defied: The dreadnought's early prototypes are seen marked for redesign due to the PD problems in simulations.
Discussed: "What's going on? Our point defenses aren't hitting a thing!"
Conversed: "Isn't it strange that The Hero never gets hit by those turrets, even though that's their only purpose?"
Deconstructed: The inability of battleships to deal with strikecraft leads to a switch to Glass Cannon carriers and fighter-centric paradigms, like with wet navies.
Played For Drama: As battleships fall to strikecraft, the factions at war desperately try to put sufficient interceptors and better PD into play while mourning their disproportionate losses.
I know you can't hit a barn's broad side even with all the gosh-darned weapons aboard this friggin' ship firing at unison, but: Could you try to hit the next link and return to Point Defenseless?