1. If you read enough, (spaced) repetition occurs naturally. No need for a software.
2. It's not bad to forget words during the learning process.
3. Purely personal: SRS reviewing is the ultimate bore, however you design your cards. And making the cards is even more of a bore. It's the opposite of fun.
It's good for 'grinding it out' type learning tasks. Example: I sat for and passed all three ham radio exams in one shot mainly because of an android ham radio exam prep app that did SRS. No way I could have done that just by reading ham radio study guides.
2. It's not bad to forget words during the learning process.
3. Purely personal: SRS reviewing is the ultimate bore, however you design your cards. And making the cards is even more of a bore. It's the opposite of fun.