Inspired Learning worth using?

On my Ranger I have a gem slot that is surrounded by 4 notables that I could easily take. I'm wondering if anybody has tried to use "inspired learning" jewel? Obviously won't be as good as headhunter, but is it still worth getting for mapping?

It's very good yes. Makes clears much much faster.

For solo play possibly, for party play no (unless you're getting pretty much every rare kill). I used it for my WB ranger until very recently and it's definitely an interesting jewel to use and can give you some pretty insane buffs (some combinations of 3+ rare mods can give you over 50% more damage compared to usual, others could make you run about 50% faster as well).

The trouble is that these buffs are inconsistent, and a lot of the rare mods are next to useless for a ranger (increased AR, bonus spirit shield, gain frenzy charges, ancestral bond, ele resistance, reflect, leech, slow enemies, allies cannot die, blessing of elements, nullifier etc), and shroud walker is even downright detrimental and will get you killed in the wrong situations.

The alternative is to use a good rare jewel, which can give life and a lot of extra base damage. This is present permanently, not just after rare monster culling. Eventually I switched my inspired learning out for this option, since the times that I actually need rare buffs most are the times when there aren't any rare monsters available (i.e. difficult boss fights), and so a rare jewel is always superior in this situation. It also lets you allocate the 3 points you presumably put into Acuity or Survivalist into something more efficient either offensively or defensively, so the tradeoff for not using inspired learning is a fairly significant permanent boost to both life, damage and/or defences.

Summary:
IL gives insane, but inconsistent buffs. Much worse for parties.
Rare jewel/passive reallocation gives smaller peak benefits, but they will always be present when you need them most.

My personal recommendation for solo would be the rare jewel on balance (unless you skip hard bosses possibly), but only if it's very good (incr max life and at least 2 high damage mods). Always rare for parties.