The HSF was unwilling to send many larger, modern TBs to assist Marinkorps Flanders. On the occasions when it did, they disturbed the British far more than the actual effects warranted (accidents, poor planning and timid execution reduced effectiveness in several instances).
But what if the HSF was willing to risk more of its light units more often? I would think that repeated, unpredictable, determined and well-planned sorties against the British drifter line, barrage forces and Downs shipping, could seriously disrupt British operations.
Sinking a couple dozen drifters at a time, two or three times, would seriously endanger the net barrage sustainability. Likewise for the Dover Straits mine barrage. This helps the U-boats.
Breaking into the Downs even once could result in the mass sinking of perhaps a hundred merchant ships -- if done properly, with little loss of civilian life. Could also prompt the neutrals to protest the British forcing their ships to concentrate in the Downs for inspection yet not providing satisfactory protection (?).
The coastal convoys were very scantily protected -- usually by one or two armed trawlers -- so striking these repeatedly might yield useful results.
And as Admiral Bacon pointed out, resources were stretched so thin that the Navy was never able to give him as many ships as he needed to secure all points properly. In fact, reading his book on the Dover Patrol makes you realize how terrifyingly vulnerable the area was during nighttime.