There is no ''account'' if you are using non-custodial wallet, and security is not affected at all with sending coins from same addresses, but maybe privacy can be affected, if you are not doing good address/change management.
Reusing addresses for receiving coins can be even worse, that is why it's recommend to generate new address each time you want to receive payment, unless it's unique donation/payment address.
I don't think it's always better actually because when you always use a new address you can't manage easily your UTXOs and when you spend one it can be joined with another one you didn't want to use for that transaction because it comes from a darknet transaction, a mixer, a casino, a sex shop or something like that. While when you dedicate some addresses to some uses and you label them you are sure to not make this kind of mistake.