It's great but it's very expensive so be aware that if you are down to the level of caring about things in the single-digit percentages of your budget, something like atop once per second could easily consume that amount of resources. A lot of these stats are really not cheap at all. E.g. you may find a substantial difference in the amount of CPU time needed to produce /proc/pid/stat as opposed to /proc/pid/statm. And some of the system-wide stats are even worse.

Yes, atop is great for this! There's also "sar" (system activity report) which can do similar things. Both are quite helpful.

Be careful running atop with the -R flag on machines that create lots of short lived threads or do lots of IO, like many databases.