The dock is twelve feet away. Your jerkbait lands beside a post, darts twice, and is already clear of it. You can keep twitching, but the part of the retrieve that matters happened somewhere else.
That is a casting-angle problem, not a rule against jerkbaits around docks. Bass may suspend near a dock float or chase bait along its outer edge. A jerkbait can reach those fish when the lure stays at their depth and travels beside the structure. A fish tucked far under the platform calls for another presentation.
Test the usable water
Count the water the lure can actually work through beside the target, not the distance from your rod tip to the splash. A cast across the face of a narrow dock might offer one useful pause. A cast parallel to its long side can keep the bait in the shadow through several darts and pauses. If there is room to pause the lure where a fish is holding, fish it. The jerkbait cadence guide covers the rod work.
Short casts can still draw a reaction strike. There is no twenty-foot minimum and no requirement that a bass follow for half the retrieve. But if every snap moves the bait past the only post you can reach, extending the pause after it leaves the target does little good. Change your angle, step back if the bank allows, or switch baits.
Depth matters too. Check where fish or bait are holding before assuming they are on the bottom. Bass can sit under a float, beside a post, or near the base. A jerkbait running beside suspended fish may be exactly right. It cannot sink down a piling on command or skip far under a low dock. The search-bait guide explains where a horizontal retrieve has room to work.
Skip a weightless worm under the platform
When the target is back in the shade, try a weightless, wacky-rigged Yamamoto Senko 5" or a similar stick worm. Hook it through the middle, skip it under the dock, and let it fall on a controlled slack line. Watch the line as it drops; a fish can take the bait before it reaches bottom. Reel up and try a different opening if it passes through the target without a bite.
Start with a low sidearm cast that touches the water just ahead of the opening. Practice the angle in open space before trying to thread it between posts. Keep clear of boats, cables, and anyone using the dock. Around branches that catch an exposed wacky hook, rig a soft plastic weedless and pitch into an opening instead. The weightless options and weedless options show the difference in rigging.
Work beside a piling
If fish are holding along a piling and you can reach it from directly above, a vertical presentation keeps the lure close to the post. A blade bait can be lowered beside the structure, lifted a short distance, and allowed to fall on controlled slack. Watch for a strike on the fall. Its exposed hooks also catch cables and submerged wood, so use it only where there is a clear path down and back up.
For a fish near the base of a post, try a light shaky head with a straight-tail finesse worm. Let it reach bottom, then make small movements while keeping it near the base. A shaky head works on bottom; it will not reach a fish suspended just below a float. Pitch a weightless bait to that fish instead.
Make the next cast count
Before changing lures, look at the dock from another angle. Can you run a jerkbait along an open edge at the fish's depth and pause it there? Make that cast. If the only useful water lies under the platform, skip a soft plastic into it. If the fish is tight to a clear piling or its base, fish vertically or along bottom as the depth allows.
The rod does not know the cast was short. The fish only sees what happens while the bait is in range.