Andreessen Horowitz have published an excellent article about how businesses should adopt to the current economic downturn, it has a central theme; 

"In a volatile market, SaaS businesses should focus on efficiency, before growth" 

Separately, Mark Ritson published a superb podcast, summarised in the post below about how companies' marketing function should respond to the different phases of the pandemic. The central point being "where possible transition spend rather than drop them"

Neither author was talking directly about the Professional Services sector but the themes of maintaining a solid marketing presence and increasing efficiency make perfect sense. Ritson showed the graph below from brandZ.  It demonstrates how much better the brands that kept spending performed coming out of the 2008 downturn compared to their peers:

However, one feature of professional services businesses tends to be that they do not keep huge amounts of cash inside the business; it is more normal that profits are distributed annually to partners and staff. This means for professional services that simply "keeping spending" as large consumer brands may be able to, is less straightforward during an economic squeeze. 

This is where Andreessen Horowitz's advice about prioritising efficiency comes into play.  A feature of Professional Services firms is that they can be rather 'political' - sometimes maintaining historic, inefficient legacy behaviours due to the way the firm is structured or the way things 'have always been done'. The sensible choice now is to look to where technology or "digital transformation" can drive efficiencies and necessary changes that have likely been known but ignored in better times. 

If the opportunity to use this economic upheaval as an agent for change is seized, it is entirely possible for Professional Services firms to simultaneously maintain their marketing output, as required by Mark Ritson, whilst also prioritising efficiency as is suggested by Andreessen Horowitz.