Advice on the copper fittings replacement

[lk777]

Hello,

A DIY guy here.

I am attaching some pictures of the kitchen and bathroom under sinks plumbing.


Kitchen Sink - Pic 1 (the Main shut off valve and the cold water shut off valve)

Kitchen Sink - Pic 2 (hot water - sink and dish washer)

Vanity Sink -Pic 3 (cold,hot and hose bibb supply lines)

My question:

I am planning to replace all 1/2" - 3/8" valves (sweat installation). Is it necessary or advisable to replace all copper fittings?

Thanks.