Annaz,
This is a good question and one to which you've already received some great responses.

I'll just pop-in to share that when I am talking about math being 30 min. I do mean just going over the textbook examples and doing the lesson in Singapore math. We also do not do flashcards or do daily drills on previous concepts. We simply go over the Singapore lesson in the textbook, and then do the workbook problems. I stay with my kiddos for math time to keep it moving along and help them over any rough spots. With Singapore math, it is truly possible to keep math to this reasonable time frame (as long as we're not adding, adding, adding to math time by adding in all sorts of supplemental books).
As far as programs like Rod and Staff, CLE, BJU, ABeka, and Saxon go... while they are solid math programs, the sheer number of problems in each assignment will double your math time when compared to Singapore. To me, this is part of the beauty of Singapore math in that I can still do a good job of teaching math and not have it rule my day or my children's day. Plus, it does a wonderful job of teaching higher level thinking and mental math.

I could go on about the benefits of Singapore math but that is not the purpose of this thread. So, instead, I'll share that with my 4 boys if I used a math program that took 50 min. to an hour each day, I would soon be at almost 4 hours of math alone each school day!

I share this to illustrate how "out-of-balance" it is for math to take that much time in our day. Otherwise, I could truly just be teaching math all day and get nothing else done!
Even though you have one child instead of four, the premise is still the same. Ask yourself, "How much time is math currently taking in our school day when compared to other subjects?" While math is important, and does garner more of our kiddos' time as they get older, it still needs to be kept in balance with the rest of their day.
I will share that on the other hand, I have an older sister who uses ABeka in the younger years and Saxon as her kiddos get older. Her math time each day for each child can range anywhere from 45 min. to almost 2 hours. In watching this scenario at her house for years, I couldn't help but feel that math seemed out of balance with the rest of the day. Her kiddos are often still doing math at night with their dad after having done it with her in the A.M. Each family has to choose its own path in this area, and you may be fine with your math time running longer. But in light of your recent thread, I do think it is a good idea to take a look at which non-HOD areas may be making it seem like your HOD day goes long!

The ladies have shared some great ideas on how to make your current math program fit into a more reasonable time frame which will hopefully help.
Blessings,
Carrie