Recently, I was part of a Stormcleave group who was lacking a Rogue. My PC was multiclassed with 5 levels of Wizard so I memorized Knock for the locked chests. I unlocked the first locked chest with a roll of 19 + caster level. We come to the second chest and I cast knock once again. I spent my entire spell point bar trying to roll another 19 to open the chest. Now in PnP the Kock spell is supposed to "open stuck, barred, locked, held, or arcane locked doors. It also loosens welds, shackles, or chains (provided they serve to hold closures shut)."
I am of the opinion that knock should be changed to instant open instead of requiring a D20 Roll + caster level. Requiring this roll hurts multiclass casters characters aswell as goes against the original spell. If changing the spell is not an option, then a second possibility is to add practiced spellcaster to the feat list. This feat could affect the casters effective caster level by 4 when it comes to the check for Knock.
I do realize that some may see this is hurting rogues, but a party can not always rely on a perfect party make up. Just like other classes, a rogue may not always be available. Clerics are not always available. Wizards are not always available. Sorcerers are not always available. Sometimes you have to make do with what you have. So this suggested change is not to hurt once class but to help everyone.
Thank you for taking the time to read this. Time to enjoy the rest of the beautiful day.