Consolidate Backup on a NAS

Hi,

I've just been on a support chat for a while and seem to be confused, contradicted in the way the consolidation works.
I have 1 backup set - full + inc no auto consolodate onto a mapped drive that is on a NAS.
Seed full backup = 220GB
55 incs varying from 1.5GB to 24GB.
total backup files = 560GB
Remaining space = 100GB.

I decided not to go for auto consolodate as I am on a laptop and need good predictability of backup duration etc. Currently at some point after lunch will kick off a backup and it takes between 10 mins and 50 mins.

So we are getting low on space and decided to start removing some versions. I went into consolodate and checked to keep all except the v1 st inc = 1.5GB. The next inc (v2) was 2.5 GB. I was expecting it to (based on docs):
- whir for a bit ensure it knew what was going on
- create a v2.1 inc that had all of 2 + anything that changed in v1, but not in v2.
-- create a temp file that max would be v1+v2
- finalise by deleting v1 & v2, leaving me with v2.1
elapsed time would be roughly time to read v1 + v2 + time to write v2.1 + a bit.
So I could start this when I get in to the office and know it would be done at some point over the next few hours.

If it does this, I can manage the history as I want / have time.

I tried and time prediction came back as 30 odd hours. It started to create a file. I cancelled it after an hour as I had desire to run out of space on the NAS / run out of time at the end of the day.
I have been on the chat to tech and initially it seemed that how I described it seemed OK, but then they started talking about needing as much space as the largest backup and it needing to read the full backup.

Can anyone who knows chapter and verse shed any light on this. If consolodate is a non-starter, then I would have started differently with a long term backup where I did it once a month and then my daily one could get deleted every couple of months.
Regards,
Jason.