i can remember the very first bass tournament i ever fished. it was on panuke lake , and my partner and i could smell a god awfull smell. as it turned out it was our butts, because the lake had been handing it to us all day. the tournament day only had 2 hours left and we had pretty much squat. the wind came up hard. we then back tracked our locations , and started cranking in spinner baits as fast as humanly possible. i can't remember the winning weight that day , but it was ours. we caught enough fish , by changing the retreive speed in the same spots that we had already fished, that we ended up winning the tournament in about 1.5 hours. we went home happy , and with SORE ARMS!
What are you fishing for, in what water temperature and time of year with what lure? Different lures work best at speeds they were designed for. You cannot reel faster than a small mouth can strike. I've seen walleye hit musky lures trolled at 6 miles per hour. I've seen catfish hit suspended crankbaits at 3 mph. I've seen carp hit downrigged Rapalas. Some spinner baits break water when fished too fast while others work well at faster speeds. I will speed up a retrieve to clear weed tops or logs etc. I will slow a retieve to attain greater depth. I will speed up when retrieving downstream and slow down retrieving upstream. I will slow a crankbait when it starts to spiral. You can pull a lure in a figure eight beside the boat and just under the surface where you can see it and judge for yourself what speed looks best. Allow for current and the speed your boat is drifting in the wind or adjust drift speed with an electric motor or drift sock.
A Bill Norman Baby N can be trolled at 3 mph and attain a depth of 18 feet. The same lure can be retrieved very slowly causing it to wobble at the surface where a crappie will strike just after sundown. The same approach is not likely to work in daylight. However, there is an exception to every rule in fishing. What worked today may not work tomorrow but there is always a reason. I am an old guy that is still experimenting and learning. You don't have to be old to catch fish but you have to experiment and learn.