Мы можем использовать rowSums
df$flag <- rowSums(df[-1] >90) == ncol(df[-1])
Или с Reduce
df$flag <- Reduce(`&`, lapply(df[-1], `>`, 90))
данные
df <- structure(list(Id = 1:4, Task1 = c(90L, 90L, 90L, 90L), Task2 = c(92L,
94L, 70L, 66L), Task3 = c(90L, 91L, 95L, 99L), Task4 = c(94L,
96L, 40L, 33L)), class = "data.frame", row.names = c(NA, -4L))