Ice cream is Good!! -- but too much Ice cream is bad!!
C25K is good ! -- BUT it also has some bad. One weakness that I see with C25K is that it tends to cause people to think that they should and can constantly strive for "improvement" -- especially in regards to times/paces. This can lead to not only injury but disappointment and disillusionment. Actually, disillusion is commonly thought of as being a bad thing - but it is actually a good thing -- because to become disillusioned means that you were suffering from an illusion all along - which is not good.
I AM striving to increase my distances and to be able to run 5Ks more easily . BUT - in regards to pace, and PB's for the 5K distance, I have decided to continue to run 5k regularly however I feel like at the time, sometimes non-stop, sometimes using intervals, sometimes slowly - and ONCE PER MONTH ONLY, I will give an attempt at a PB a good go. My local Parkrun has, once per month , a "pacers day" - the fastest pacer starts at 20 mins and then they range out to 35 minutes in 2.5 minute increments. I have already "broken" the 35 minute mark with 34 minutes and 12 seconds - so at the next one ( in a fortnight) I will try to follow the 32.5 minute pacer. Regardless of what results, I will then forget about 5K times until the next month comes around.