I've listened to the audiobook call 'Bounce' by Matthew Said. He claims 'purposeful practice' is the key. Many, many, many hours of it. I'd recommend that book.
See you in the nets!
'Bounce' is a superb book. I studied Sports Psychology at Uni (way back when, I'm in my late thirties now), the most inaccurate term is 'practice makes perfect.' If you think about it, its the most ridiculous statement.
More accurate is 'practice makes permanent.' It could be perfect, it could more likely be not. However you practice/net, will groove technique, but if you're doing it wrong, it won't be perfect.
Similarly, as you quote Syed, what's the point in practice if its not purposeful? How many times do you visit a gym, to see people sat on bikes or on cross trainers checking their phones? Its a social experience, as nets can be for players - but is it making them fitter/better? Not likely.
Therefore everything you do should be purposeful to you. It may not be perfect, as clubs may not be lucky enough to have qualified coaches on hand at every net, but you should be able to self-analyse and test yourself, be that through disciplined play (remaining not out/not slogging, etc.) or working to groove a technique, especially with a bowling machine.
We had out first club nets on Friday. Three or four players came out after slogging a few, getting bowled, yet hitting 3-4 good shots in 10 minutes and all said "good net that, great to be back straight into form" ?!?! You were probably out caught for 4 or bowled for 8!
I would suggest that regular purposeful practice is the key for those not lucky enough to have access to one-on-one sessions or a bowling machine...