How Much MDF Primer?

Hi all, we've just had wardrobes built by a local tradesman and I'm in the process of priming the insides before painting them. I've read that you need to apply two coats of primer to mdf before painting in order to seal it, but is two coats of primer really necessary for the insides? Totally appreciate that the doors will need two coats before painting but could I do one coat of primer followed by my top coat on the inside sections? Thank you!