Historically I've just accepted that I am a slow (but strong) swimmer wth IM splts ranging from 1:07 at IMAustria to 1:12IMNZ. Now my swim efforts varied between 4 swims a week of 3.5-4km for 6 months before the race, and not getting wet until 2 weeks before the race. For reference then my pool times tended to be about 8:00 for 400m as my legs sink (#cyclistexcuse)

This year in the off season I decided to really focus on swimming. Took my technique to pieces, made an effort to swim 4 times a week. And that did mean I was swimming differently, but honestly not that much faster. Then through injury that stopped me running I swapped to do a few more squad sessions. So 3 squad sessions a week and 1 technique session.

This week I did a 6:36 400m as part of a test set and that was felling very very easy, about 3 weeks ago a 27:00 1500m (in a 'slow' pool). So I'm no thorpe, but all of a sudden then I am a mid pack swimmer.

Anyway, back to your point. We do a fair bit of pull buoy and paddle stuff, but we also do quite a bit of (just) kicking. It's taken a while, and it's still a bit of a weakness for me, but feeling the kick is important. What I've found is that swimming is really frustrating, as unlike the bike or running then simple effort does not lead to improvement. It's so much more about technique than strength / fitness that you really need that feedback in parallel with your effort.

I also found that whilst I'd always much preferred to train on my own as it was more time efficient, then actually going to 1 hour squads and allowing for an additional 30 mins travel either side, meant I was still being more time efficient in actual benefit to my swimming than a week of solo sessions. No matter what you do in terms of sets with / without the toys, then having some feedback as to what's working, what's not, what you are doing different when your stroke falls to pieces as you fatigue is the key.