Economy Rate is more important in Tests, an economy rate of 2.50 compared to 3.00 saves you 15 runs over 30 overs.
Nathan Lyon and Shane Warne have roughly the same strike rate of 60, same as most Test bowlers.
Acccurate bowlers like Mohammad Abbas, Wiaan Mulder, and Kyle Mayers do well in Tests, but their good Test length becomes the slot in T20s so they are useless T20 bowlers.
Legspinners are a liabilty in Tests, on a raging turner all you need is accuracy, finger spinners always do better in Tests.
Also in Tests, Strike Rate generally determines Batting Average, most batsman average about 100 Balls Per Dismissal.
Test stats are all determined by Strike Rate and Economy Rate.
T20 stats are all about Averages, the rest are all about the same over a 20 over innings.
Everything they told you about cricket stats is wrong.