When I install a sims 3 pack I always save it in my mods folder but I just realized that the sims 3 packs save automatically in the downloads folder (I think all of them save there but I don't know there were too many to check). So should I remove the sims 3 packs I put in my mods folder? I put them there as a backup if I would need to install them again but if they take up space it would be better to remove them from the mods folder since they have no real use there.
Your mods folder is for installing packages, so having sims3pack files there won't make any difference.
Once you install s3packs, you don't actually need to keep them anywhere, and it might be worth taking them out of your downloads folder once installed so they don't clutter up/slow down the launcher.
If you want to save them somewhere for safe keeping, you could just put them somewhere else on your hard drive rather than in your game folder, or even on an external hardrive if you want to save space on your computer
I second Zoe22, and highly recommend saving your sims3packs to an external or flash drive if you have one. Leaving them in your mods folder can potentially inflate the load time of your game. Even though the game will not load sims3packs from the mod folder it still has to read them during startup. Same goes for any files in the mods folder which is why its best to only have package files in as few subfolders as possible.
Also wanted to add incase you're not aware that when you use the launcher in install sims3packs it will also save the content in package format to a folder called DCBackup. The content of this folder can (and is recommended) be safely deleted EXEPT for a file named ccmerged.package. This file is required for premium content to function properly.