How can I think more strategically and broadly during case studies? Do you recommend any books, or does this skill come with time and practice? My current approach seems too superficial.

I have good news for you, you don’t really need to learn frameworks. Some are useful, but chances are you will get very strange cases you cannot solve with a learned framework. 

And, however often you hear that you need to think in a certain way… it’s not true.

Step 1: Dump All Topics you can think of in the Middle of the Paper

• Seasonality
• Price
• Competition
• Gym’s Condition
• Occupancy
• Contract Length
• Customer Retention
• Gym’s Visibility
• Marketing
• Location
• Services Offered
• Customer Demographics

Step 2: Group into Themes. Write categories on the left-hand side of the paper. 

• Customers: Customer Retention, Customer Demographics
• Pricing: Price, Contract Length
• Competition: Other local gyms, alternative fitness options
• Operations: Gym’s Condition, Occupancy, Staff
• Services Offered: [BLANK]
• Branding: Gym’s Visibility, Location, Marketing
• [BLANK]: Seasonality 
  Note: do not worry if there are blanks at this stage for topics you cannot assign

 Step 3: Check for Breadth by always double checking for the following:

• Stakeholders:
  • Demand Side: Current members, potential members, lapsed members
  • Supply Side: Gym owners, staff/trainers, suppliers, investors
• Environmental Factors:
  • Economic conditions (e.g., recession)
  • Health trends (e.g., yoga is trendy now)
  • Technological advancements (e.g., fitness apps)
  • Local regulations

Step 4: Check for MECEness. Enhance the existing list with any relevant items you discovered in Step 3:

• Include staff and suppliers into operations
• Expand list with Investors and Gym owners
• Expand the list with Environmental factors
• Include seasonality into environmental factors

 Your updated list now looks like this:

• Customers: Customer Retention, Customer Demographics
• Pricing: Price, Contract Length
• Competition: Other local gyms, alternative fitness options
• Operations: Gym’s Condition, Occupancy, Staff
• Services Offered: [BLANK]
• Branding: Gym’s Visibility, Location, Marketing
• Environment: Economic conditions, health trends, tech, regulations, seasonality
• Investors: [BLANK]

Step 5: Check for Depth. For each theme, you can add detail by using what, when, where, how questions (as applicable):

• Customers: demographics, peak times for sign-ups/cancellations, member locations, reasons for joining/leaving
• Services Offered: types of sports, delivery methods (e.g., online, group classes, individual sessions), membership benefits (nutrition guidelines, protein bar, therapist,…)
• Pricing: pricing tiers, promotions available, price sensitivity, value perception
• Competition: location of competitor gyms, customers, services, pricing,…
• Operations: equipment condition, staff qualifications, maintenance schedule, opening hours, layout
• Branding: brand image and fit to customer demographic, marketing channels, campaign timings, referral programs
• Environment: economic conditions, health trends, sports trends, technological advancements, regulations, seasonality
• Investors: expectations, requirements, concerns

Step 6: Refine the topics with Hypotheses. For each topic, ask "Why would this topic affect the problem at hand?", i.e., “why would this topic affect revenues?”

• Customers: targeting wrong demographics, opening at wrong times, operating in the wrong location, not offering desired services (see next)
• Services Offered: offering unpopular sports or setups (e.g., not in groups, no individual coaching, no nutritionist services)
• Pricing: too expensive for what is currently offered
• Competition: nearby competitors with better perceived offerings for the target demographic
• Operations: poor equipment condition, unqualified / unfriendly staff, conflicting maintenance schedule, inefficient layout
• Branding: using wrong channels to advertise to target audience
• Environment: economic downturn, new health trends not serviced, lack of technological integration, not leveraging seasonality for promotions
• Investors: focused on cost-cutting affecting quality of operations

Step 7: Think About Data. Identify the types of data needed to test your hypotheses: 

• Customers: demographic data, satisfaction surveys, retention rates
• Services Offered: list of services, usage statistics
• Pricing: pricing tiers, volume of sales by tier, promotional impact
• Competition: list of competitors, their services, and pricing
• Operations: equipment renewal records, maintenance schedules, staff qualifications, number of staff (FTEs)
• Branding: marketing channels and campaign performance data
• Environment: economic indicators, health and sports trend reports
• Investors: investor expectations, reports on cost-cutting measures and their impact
   

Step 8. Order how you will present your thoughts.

• State out loud that you have thought of several categories, for each you have hypothesis on how they could contribute to a revenue decline, and that you have some ideas on how you could confirm each.
• Then present the categories. 
• Then lay out your hypothesis from most plausible to least plausible.
• Then say the data you would look for to confirm them.
• Finally, ask the interviewer if these make sense

Starting from a page that is not blank is a lot easier than trying to be structured in your mind from the beginning. 

Train finding categories and asking questions to initial ideas and you will naturally get better at both structuring and being creative. 

The examples I am giving above are not even that creative and they would be enough to come across as thoughtful and as someone who has full ownership of their work and is capable of driving the case autonomously.