Hello D. Omar,
We have 3 major releases per year - Q1, Q2 and Q3. This means that you get a major release on every 4 months.
We keep any major changes or additions for these release. We also have official service pack releases which are generally twice per Q release. Those service pack releases include mainly bugfixes and small improvements for the controls. If you do the math you will see that we have release roughly on every 6 weeks.
You also noticed our "latest internal releases" - they contain mainly bugfixes and are available at the end of each week.
I hope this give you some light on our release cycles. Our next major release (Q2) is scheduled for this week.
the Telerik team