Aws snapshot management

We have an account with aws and we see that we have an overspend on the snapshots created , we either forget to delete them or it gets piled up leading to snapshot usage costs. We have an algorithm , where in

1) we have 10 volumes whose snapshots has to be taken twice a day which sums to 20 snapshots a day

2) We will have 140 snapshots at the end of first week, once the second week commences we follow step 1 and retain only the snapshot of the last day of the first week

3) we continue step 2 for for the rest of the weeks

4) At the end of the month we have 80 snapshots and at the end of the first month we retain only the snapshot of the last day of the month

5) So if step 4 is followed we will have 240 snapshots per year

This is the psuedo as it seems to be tough to implement with a script or an aws cli. Is there any tool you could suggest to delete and create snapshots from central point. Or is there any script which can do this. We already had a look at Skeddly , are there any alternatives for this tool itself. Please do help us with this