What was the significance of the reforms in the 1550s?

The reforms of the 1550s were the most successful in that century before Russia, surpassed in quality only by Tsar Alexei Romanov, who ruled 100 years later. The results were as follows:

A streltsy army appeared, that is, partly regular infantry with firearms, at first there were 3000, then the number increased to 10-12 thousand. The army turned out to be reliable and the last streltsy regiments existed until the beginning of the 18th century.
A new set of laws appeared (Code of Laws of 1550), it operated for 100 years, a new body of the estate-representative monarchy appeared – the Zemsky Sobor, it existed until the 1680s.
The effectiveness of local governance has improved due to the abolition of feedings and zemstvo and lip reforms.