I have been with Skinny/SkinnyDirect since the very beginning and they are great. I have no desire to change. Naturally I want to eke out as much mobile data as possible for my dollars. I very rarely make voice calls or send SMS. Their updated iOS app makes this very easy. This is what I do to maximise value.

I buy the $66 plan once, which gives 30gb rollover data. Then for next 3 months I buy the $16 plan, which adds 1.25GB rollover data per month.

4 months [28 days each, not calendar months, I know] costs 66+16+16+16=$114, with a total of 33.75GB rollover data, for an average cost of $28.50 per month, with 8.4GB data per month.

By comparison the

$26 plan over 4 months is $104, with 10GB data total, 2.5GB per month
$36 plan over 4 months is $144, with 18GB data total, 4.5GB per month.
$46 plan over 4 months is $186, with 48GB data total, 12GB per month.

So doing this gives WAY better value than buying the $36 plan each month, is $7.50 cheaper per month and gives nearly double the data.