In this day and age, there is no guarantee of that next interview or class date.
Not to sound negative, but if you want the job, a bird in the hand... as the old saying goes.
Some prospective employers may gauge a person's interest by the effort they take to make the interview when offered.
Many companies hire to fill an immediate need. Maybe the need will be there for a while, but then again, maybe not.
"Ya pays your money and ya takes your chances!"
Just my $.02.