Firstly, helitrox adds
no additional effort. It does remove narcosis but at a cost and is exceedingly useful if diving beyond 40m/132' (depending on your own narcosis reactions).
Simply put, it opens up opportunities. In my case, helitrox gives me access to loads of wrecks in the 40m/132' to 45m/145' range. These can be more interesting and are often further out in clearer water.
If your diving doesn’t fit this kind of profile, then it’s obviously not an enabler for you
Secondly, AN-DP.
Advanced Nitrox teaches you about rich mixes and the issues it brings. This is all to do with the effects of oxygen, including Partial Pressures, Max Operating Depth (MOD), Central Nervous System (CNS) limits and Oxygen Tolerance Units (OTUs) which are simple tables. All calculated in MultiDeco et al.
This boils down to planning your gas for the dive and correctly labelling your cylinders.
Decompression Procedures is the theory of decompression — essentially so you can take part in the endless Gradient Factors discussions (why 10:70 is silly whereas 50:80 is more effective).
In water skills are all good stuff for a competent diver, plus gas switching procedures.
What all this does is opens up opportunities for you to to safely extend your dives past the recreational diving limits. This is particularly relevant when diving over 30m/100'. Whilst this may not currently be your current dive profiles, you will appreciate it if diving elsewhere. UK wrecks shallower than 25m/80' are far less interesting and limited than wrecks down to 40m/132' (nicely achievable on 28%)
In summary, AN-DP is an enabler. What is behind that door?