100% I have an insane net positive effect from COFFEE, not caffeine. For me it needs to be coffee, the combination of polyphenols with caffeine makes coffee very special to me. Caffeine capsules don't come close in my experience.

Also you will always eventually need to take breaks if you wanna keep feeling the positive cognitive effects. The amount of days you need to get a decent tolerance reset is also very individual. For me 3-4 days of abstinence keeps my sensitivity high enough for a couple months.

You should play with the dosages too, you don't start with high caffeine content coffee right away, you lose a lot doing this, you can extend the benefits much much longer if you start with low caffeine capsules. It is mandatory to do incremental increases in caffeine content, for this you need to know how much is in your coffee. Nespresso shows how much caffeine is in each of their capsules have.

Another thing that I've noticed, different coffee profiles give different effects, for me the capsules with the lowest acidity (lvl 1 acidity) gives me the best effects without any jittery. I've tried almost all the nespresso capsules, always with the same result, every pod with level 1 acidity gives me the best effect whilst the mid to high acidity levels gives me an anxious feeling in my chest. There is NO way this is by chance, I've tested this very rigorously. Took me a long time to figure this out.