Hoping my new Severne adjustables work well, old ones were terrible

My adjustable Severnes were terrible to start with, always slipped. Then after a few week the webbing got all stuffed up and now they work perfectly.

I have been using the Maxsoir monolines on my Raceboard for a few years now and find them really good.

I'm currently using the following on different booms :-

1. Dakine adjustable (not easy to adjust length on the fly). Non see through plastic tubing (see my final comment below on this)
2. ION with camcleat (work great, but tend to grip on the boom making them hard to adjust position along the boom while racing). Also the velcro on one boom attachment freyed within about 1 month. Non see through plastic tubing (see my final comment below on this)
3. Chinook with camcleat very similar to the ION's but easier to adjust along the boom and the rope is replacable (reuse the boom attachments), also has see through plastic tubing (see my final comment below on this)

All 3 are fiddly to attach to a boom and require the boom end to be removed. Not great if you break a line in the middle of back to back races (too slow to replace which results in missed races).

I'm going to buy the Nautix with Camcleat, they can be very quickly installed on the boom without removing the boom ends.

Also beware of any lines with non see through plastic tube covering the rope. You cannot see if the rope is damaged inside the tubing which can result in failure mid racing, which is what happened to me recently on line only 1 year old that looked in good condition elsewhere.

I like the NP ones they stay put.

+1 NP lines but i'm not constantly adjusting them, if you do then something like max's lines would be better.

But the NP ones, I found are good size range & have worn out tubes before the line has started to slip which has been an issue with others.

What is the benefit of adjustable lines. What is wrong with using the same length all the time.