I thought some of the other members of the forum might have chipped in with a comment or two by now, but it seems not. :-X
Jumping back a stage, I would always recommend that anyone learning Morse gets as much receiving/decoding practice as possible. Although listening to hand sent Code is the ultimate aim, I sometimes wonder if learners might be better listening to 'perfect' Morse sent by either a dedicated Morse Tutor, or from a PC/mobile device running suitable programs.
A good deal of Morse off-air I've found is very 'sloppy' on the timing these days, plus you will get folks that try to put their own stamp of the thing, imagining that their style or fist shows them to be somehow 'special' or cleverer than other operators. To my way of thinking the further someone deviates from perfectly timed code the more difficult it becomes for anyone else to decode it.
The argument used by such operators that if you were experienced enough then you would be able to read their 'offerings', and that YOU clearly need more practice to 'come up to their level of expertise'! ;D
If you listen to perfectly timed Morse on a regular basis you find that when you then start to send, if you listen to what you are sending you will spot the timing without even trying. Mistakes, or rather deviations from the norm stick out like a sore thumb.
It's well worth recording the Morse you send while first learning, and then listen to it played back, not necessarily straight away but a short while later (to give you time to forget what you sent and in a way then force you to actually read your own code). This can prove a real eye opener at first!
OK, moving on to your original question, I really don't think that using an electronic keyer is that beneficial, since you need to know what good code sounds like AND be able to send well timed Morse yourself, without relying on any 'aids'.
Bug keys and paddle keys+keyers do allow an operator to send faster, everyone has a limit on how fast they can manipulate a key (no matter how much practice they undergo), but you should not need to
rely on them to correct your mis-sending.
Something I hear a lot on air is folks using keyers to blast away at ridiculous speeds, but they still have really crappy timing when it comes to spaces between letters and words. You hear what seems like one long stream of dits and dahs without any recognizable gaps to speak of. If they were actually listening to what they were sending AND instinctively aimed for perfect (good) timing, then such garbage would not leave their antennas! :
So always aim to send Code with as perfect a timing as you can muster, always listen to what you are sending with a critical ear, and beyond that it will not matter whether you are using a ?1000 straight key, some super-mega keyer and paddle, or simply touching two bare wires together, as you Code will always sound excellent at any speed.
There are no shortcuts!
73, Mark...