RMSR says "must be able to cast it at least once a day (either intrinsically or from an item)" on page 167, but if you turn the page and read the fine print on 168 it says "must be able to cast it without the need of a spell roll at least once a day, either intrinsically or from an item or runes (i.e., it cannot require overcasting, etc.)." So that actually matches SoHK.
The mention of runes is interesting, because if you can qualify with single-use items that raises the question of how many days you need to practice and therefore how many runes would you need to buy?
The restriction seems pretty steep to me. As written, at 6th level a Magician could not have any ranks in Directed Spells: Fire Bolt, even though they could cast the spell. Can't develop them until 7th. And likewise they could not have any ranks in Directed Spells: Shock Bolt until 3rd level, even though they can cast it at second level. Of course if a GM wants to skirt that, they can easily give the character a daily item, but still. Overcasting by a single level outside of combat is quite easy in RMSS. With a realm stat bonus of +5 and five ranks in a list, you could be rolling at +85 (+50 base -10 for max prep +10 deliberate action +10 shout +5 base list +10 +5 stat +5 ranks), with success on a result of 76 (partial success, spell goes off the following round). To me, that seems reliable enough for practice. Yeah, maybe once every three weeks (4.4% of the time) you might fumble the spell and suffer a few hits and a little stun, but that's part of the learning experience. More ranks (e.g. at 4th level you could have 15) and a better stat bonus would mean casting fire bolts even at 4th level is even safer (another -5 for overcasting by an additional level, but +10 for the additional ranks).
And some flexibility here would allow a 1st level magician to overcast those shock bolts and maybe occasionally hit something lightly armored.