I agree in principle Russell - harder implements - or those with a high terminal velocity are not safe in untrained hands. If you wish to use whips (bull, signal or cat), learn how to wield it on an inanimate target first - learning control and finesse. The lovely popping sound a whip makes is a result of the tip traveling above the speed of sound. You generally do not want to consistently hit your sub at over 700 mph - you'll cut her badly and can leave some very nasty scars. Learn to time the impact of the tip to just after the pop, when the speed of the tip has dropped considerably.
In terms of whips (and this is my perspective, others are free to disagree) - once you have learned how to use it well, more frequent use is feasible - just not over the same part of the body every time - and never days of hard strokes in succession. My girl always wears fresh stripes - they take a day or two to fade, but some part of her body has fresh whip stripes all the time, unless, for some reason we have not been able to play (illness, for example). However, unless she moves unexpectedly when a stroke is in progress, I don't raise welts or bruises, or break the skin. I prefer daily play - and find that by being careful in how I administer strokes, we can and do play daily...we would not be able to do that if I raised bruises. welts or cut her, since I refuse to administer the whip when there is skin trauma. I also address a different part of her body with the whip on subsequent days - perhaps her back today, her breasts and belly the next, her bottom and thighs the third, though I do use my hand, a flog or crop on whipped areas that are 'out of play' at the moment.
The real key - is practice, practice, practice until you can land a stroke precisely where you want it to go consistently, avoid deep trauma to the skin, stay away from easily damaged parts of the anatomy, and above all, know your slave/sub well what she can tolerate and what she cannot, what is likely to trigger an unexpected reaction, and how her body responds in terms of bruising and marks. And understand when aesthetics may be counter-productive. I had a girl once who just didn't bruise unless you were on the edge of bruising muscle. While stripes or a deep rosy mottling might have looked good on her - getting her to that point was too close to the edge of doing serious damage - so she was never taken beyond a pink glow. She was a delicate girl - but she had a hide like a rhinocerous - lol.
I am much less fond of canes or split bamboo - and use them sparingly - and refuse to go to the point of welts...and the paddles I prefer have a large surface area and are less traumatic to the skin.
After-care is vital, as Russell says - regardless of the implement used - even a friendly otk deserves after-care - - and after-care is highly enjoyable too.