Well, depending on what you evaluate your labour as, it may be a job worth doing. But commercially, and given that labour is a major part of costs, and even for 12 sq ft showers, we find a jackhammer more efficient and less costly. Small electric ones would do the 300 sq ft in about an hour, barring any complications.
Now if you're doing this for your mother-in-law, you could take all weekend to do it - and she'll supply the beer and supper too! (sometimes that's not a bad deal)...but if you value your time commerically and hope to be in and out of there soonish, you're best to look at better efficiency.
Bathroom floor demo is a common occurence amongst people who do this repeatedly and I don't think there are many who, using a jackhammer during the day, would do their own mother-in-law's bathroom with a hammer and chisel on the weekend no matter how good a cook she may be.:laughing: