Riding for 5 weeks and worried about technique!! Think I would still be worried about Butt ache.
The cadence (RPM of the pedals) that you are thinking about- Don't think about it much. Reasons for a higher cadence are numerous- but the common reason is to take strain off the legs and joints. By pedalling faster- and staying in a low gear- then speed will not go up but strain will go down.
If you are worried about it- measure your cadence now at say 15mph (Or 10 ) and at your usual pedalling rpm. Count the number of revolutions in 15 seconds and multiply by 4. For a beginner- this is usually about 60. Lower and you could be in trouble- higher and you are getting there. To increase cadence- get to a speed and in your normall pedal rpm. Then change one gear lower and keep the same speed. Takes practice but gradually your cadence will go up.
In the mean time- just get on the bike and get fit(ter) and enjoy the ride.