Using a PC cleaner on a system is completely a personal choice for the owner of the system. Although it has several benefits some people actually do not prefer using this kind of software on their personal computers due to the few reasons such as excessive battery consumption and space consumption. I am not sure if you will be able to save a ton of battery life or space by not using a good PC Cleaner software but I am pretty sure that there are several downsides to not using one.
If you are not using a good PC Cleaner from time to time there can be several severe complications that can arise in your computer. One such complication is slowing down of the computer in performing day to day tasks. This is a serious issue that can arise in your computer in case you are not using a good PC Cleaner as the junk files and unwanted residue can clog several other applications hindering the free usage. It is much like cleaning a sink. If you do not clean the sink over time and allow it to clog it can overflow with water very easily, however, if you do clean it, you will not face any kind of problems. Therefore it is a good idea to have a PC Cleaner software to take care of the PC unclogging.
Another major problem that can arise within your system is slowing down of your browser and a potential threat to your security. In case you use a PC Cleaner software, it will clean your system of saved passwords and login user IDs (if you decide it to) and this will ensure that the cache files on your computer are not decrypted in order to reveal sensitive information which can be severely misused.
The software also speeds up the booting time of the computer by shutting down or removing bloatware applications that are battery and power intensive which then allows the user to gain faster access to his/her machine whenever necessary. It also works as a privacy protection antivirus keeping you browsing history secure. Hence, it is a must to use.