Using multiple addresses is only theoritecally less secure than using only one for multiple transactions. Any way you would expect way more than a lifetime to crack your wallet.
But if you put your private keys in risky situations(connected to computers with internet, at reach of other people that might have the idea to stole it, etc..), sooner or later the change of your keys being compromissed will be high, then it might be a good idea change address from time to time.
When you use a new address each time you send a TX you will generally use the same wallet. You also do not need to actually send a TX to potentially compromise a wallet if you have it open/loaded on a computer that is potentially compromised/risky.