I see you've only been in business as an seo for a year... but even with that there is no chance you could not be affected by an algorithm adversly in that time... unless you have no clients in competitive niches I guess.
Its painful to read such a naive comment from someone selling seo as a service...
Because there are multiple noticable algorithm changes every single month!!! The best you can hope for is to come out of the
month ahead, not out of every single
algorithm change ahead.
If you're only playing in hobby niches then sure you can take 1st place in 3 weeks and never lose it... if you are competing for high value phrases slight dips in rankings are inevitable.
Its funny watching seo sellers take the high ground here... nobody is saying you are a bad seo if you have a bad day in the search results. Are you all worried people will be put off hiring you if you admit an algorithm change can dip your rankings for a week :|
But what you are suggesting is similar to Messi saying he's never made a single bad pass across a full season - its complete nonsense, and impossible. He'll still win all the trophies and have the glory at the end of the season but there will be the occasional bad day mixed in along the way