Pretty accurate but more importantly you just need something with the correct framework (which Semrush definitely has).
If your website truly receives 2,000 visitors a day but analytics only shows 1,000 visitors and you use analytics to measure your results.
Then you measure 1,200 visitors in analytics you’ve had a 20% increase… The actual number doesn’t matter. You’ve done a great job improving by 20%.
If in reality you had 2,400 visitors. Does it really matter? The key is improvement.
Pick a tool (any reputable tool you can afford) after you do your research and use it consistently. A consultant who uses another tool to get metrics may get different results which could incorrectly imply the work that’s being done isn’t working which would be wrong.
Once you pick a tool, pick a measurement framework (KPI’s), and stick with it as a way to measure input vs results.
If you’re in position 56 according to Semrush but you change to SE Rankings and all of a sudden you’re in position 33… You didn’t just improve 23 positions… You changed software.
If you’re in position 56 but move up to position 44 on the same platform… Great work! You just improved 21% Keep pushing!
Hope this helps!
P.s. Semrush is a great tool, it’s just on the expensive side of tools (mostly because it does so much).