I run my campaigns in eberron or an eberron-like world where libraries and such are common so have some experience with easily available spells to copy for wizards. It depends on:
- The level of your game
- The level you expect the campaign to run to
- How much gold/downtime is available
1&2 If the game is low level & expected to stay there it can be a significant boon given adequate
3 because nearly all of the maybe useful ritual spells are 1st-2nd level spells with lie one 3rd level spell(tiny hut). The problem is that the vast majority of those spells are so deep into edge case niche territory that they would otherwise not likely ever be worth taking or rally even spending much on scribing.
If
3 is too restricted then the benefit is meaningless as the nice nature of ritual spells & wide assortment of 5e's unused by design spells make it into a benefit not worth using even if the player can.
As the game advances beyond low levels into mid (6-10) levels the benefit of having all those ritual spells melts away as it's clear that the vast majority will never get used by now, are easier handled by classes with a relvant skill/ability, & other classes have powerful class features by now. In short, the early benefits are nullified without
this sounds like a job for aquaman contrived situations because the ritual spells don't continue to grow in the spell list & the o5e spells themselves lack any meaningful choices beyond a few must take "
iconic" spells in a sea of trash by design spells.
Most of my campaigns run into low to mid teens so I can confidently say that from 11 on up the benefit is almost pointless. There are a lot of things that contribute to this
- First there is the continual slowing of spell slot acquisition that begins at level three
By level 7 it's almost at a standstill & at level 11 there is basically no more slot acquisition. Because of this a wizard IME is likely to devote the additional prep slots they are gaining towards lower level spells that were not good enough to make the always prep list like dragonbreath so they can send their familiar out to do something if the party is using tiny hut as a bunker during a rest or whatever.
- The math is absolutely bonkers against casters from the getgo & gets worse as fighter/warlock/scorlock accumulate additional attacks at these levels martials are likely to get magical gear that makes things even worse. There just aren't enough high level spells to make the what to prep for that one slot an even trivially difficult choice so having a larger selection of them is not even a theoretical benefit.
- Nearly every spell if not literally every spell in o5e when upcasted is either exactly the same or worse when rated on a scale of x benefit per slot level as upcasting causes the value for x to shrink more & more the further you upcast. The wizard won't be looking back & dogging up new gems that were previously not useful like in 3.5 when spells often went from pointless to good or great as castr level improved.
- Agonizing repelling blast in o5e at this point is easily the equivalent of a 4th or 5th level spell when rated against dmg284's spell damage chart allowing a warlock or scorlock/pallylock/bardlock with 2 levels of warlock to cast it at will as the cost of one barely useful spell slot. It's hard to ignore everything above & find any real strength while blistering under the nuclear furnace of fighters extra attack/agonizing repelling blast with a straight face. Levelup corrects this to some degree by making EB a warlock class feature but we don't have the spells yet
- Levelup's rare spells likely add some amount of extra value if they are in that library but at this point we don't have enough details to guess at how much value.
TL;DR version? In my last campaign with a wizard player I gave them a spellshard with a zero cost scribe cost, plenty of downtime, & made libraries like that available but I'm pretty sure they were
never used after level 5 & barely used before that... That game ended around level 14.