Gas compression/decompression question

Am I right in thinking that if I compress gas and have the gas Efficiency Skill at V I LOSE 15% of my total gas haul?

almost correct… Free to compress but a loss to decompress.

One of the industrial updates for null-sec to get enough gas to build(in theory). Gas takes up a lot of m3

That seems like an excessive loss at level 5, you may as well not bother with the skill

You only lose 5% if you use a Tatara and have max skills. You do not lose any gas when you compress it.

Well you do not have to compress.

If you can sell or use the gas locally I wouldn’t compress at all. Or if you can haul it to where you need it and do not mind making the trip a few more times to move the gas in uncompressed state, then I wouldn’t compress either.

There will be a point where the tradeoff of moving compressed gas starts to be preferable --even with some losses-- compared to moving much larger volumes of uncompressed gas.

If you haven’t reached that point then yes, you may as well not bother with the skill.