Personaly i like shorter harder kicks,
theres a great exerces.
Do a length under water,start off with a huge long kick then as you proceed shorten your kick as you go,taking acount intoy your acceleration and find the kick that works best for you,meaning which part of the pool you feel fastest in.
I have'nt reaped the benifits yet as i'm still working on it but i generaly like 3 quarters way up.
Another
Go to the surface and work on one leg,finning only,pushing downwards and concentrating on pulling upwards as well,do a few of those lengts alternating as you go.
You can look under your body and make sure your fins are horizontal flat to the the pool bootom,thus giving you as much forward thrust as possible,you would be surprised how many people have a bandy kick.
Theres also toe and ankle extensions to the kick,which are a bummer for me.

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top of de mornin to yeh