A client of mine (name withheld*) related to me an interesting anecdote with regards to guitar playing:
I read or heard somewhere that if you practice a piece but allow mistakes to seep in, all you’re doing is practicing mistakes. If you take 40 minutes to play a 20 note passage perfectly, you’ve practiced it once. If you go - Do do do do do do *slop* “Damn!” Do do do do do do do do do do *slop* ” Crap!” - then you’ve already practiced making that mistake twice. Your brain doesn’t know the difference between playing the piece properly or not (sic); you’ve got to teach it the right way to play.
What n.w. is saying is that practice doesn’t make perfect. Perfect practice makes perfect.
Why is this an important concept? Because it directly applies to lifting a heavy (for you) weight.
The act of lifting a weight (i.e., performing a resistance training exercise) is a skill. And just like a difficult passage in an Albeniz piece, performing a resistance training exercise poorly by jerking or heaving the weight (vs lifting it strongly and smoothly), whipping your body around (vs holding yourself stable), or involving every single muscle in your body (in the wrong way) is not only is a poor showing for that particular exercise bout, but sets the stage for imperfect practice later on as well.
The moral: Treat every rep (yes, every rep) as an opportunity to deliver perfect form. Will your form be perfect? No - especially if you’re new to strength training or you’re on your last reps - but that’s not the point. Your attempts at maintaining perfect form - that’s the point.
Incidentally, this also means that the last rep you can do in good form is the last rep you should do. Yes, you should sometimes push the envelope - flip the switch, so to speak - but be sure you’ve learned good great technique first.
Of course, I’m not the only one to advocate this. Pavel has been preaching the virtues of treating your weight training as skill work for at least the last 20 years (as I’m sure my friend Nikita will be happy to hear me admit).
Treat every rep with respect. Perform the initial, easy, warm-up reps of your exercise as skill rehearsal. Make all the “working” reps of your exercise as perfect as possible. And please, hold it together in your final “death-throes” reps - for your safety’s sake. OK - practice time!
*While I’m not at liberty to say who this is, take it from me that as a world-renowned guitarist for a multi-platinum selling band, he knows what he’s talking about.